Resist composition, compound, polymeric compound and method of forming resist pattern

ABSTRACT

A resist composition comprising a compound (m0) (wherein Rb 1  represents an electron withdrawing group; Rb 2  and Rb 3  each independently represents an aryl group, an alkyl group or an alkenyl group, provided that Rb 2  and Rb 3  may be mutually bonded to form a ring with the sulfur atom; and X0 −  represents a monovalent counteranion).

The present invention was made pursuant to a joint ownership agreementbetween Tokyo Ohka Kogyo Co., Ltd. and SAN-APRO LTD.

TECHNICAL FIELD

The present invention relates to a resist composition, a compound, apolymeric compound and a method of forming a resist pattern.

Priority is claimed on Japanese Patent Application No. 2013-115542,filed May 31, 2013, the content of which is incorporated herein byreference.

DESCRIPTION OF RELATED ART

In lithography techniques, for example, a resist film composed of aresist material is formed on a substrate, and the resist film issubjected to selective exposure of radial rays such as light or electronbeam through a mask having a predetermined pattern, followed bydevelopment, thereby forming a resist pattern having a predeterminedshape on the resist film.

A resist material in which the exposed portions become soluble in adeveloping solution is called a positive-type, and a resist material inwhich the exposed portions become insoluble in a developing solution iscalled a negative-type.

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have led torapid progress in the field of pattern miniaturization.

Typically, these miniaturization techniques involve shortening thewavelength (increasing the energy) of the exposure light source.Conventionally, ultraviolet radiation typified by g-line and i-lineradiation has been used, but nowadays KrF excimer lasers and ArF excimerlasers are starting to be introduced in mass production. Furthermore,research is also being conducted into lithography techniques that use anexposure light source having a wavelength shorter (energy higher) thanthese excimer lasers, such as electron beam, extreme ultravioletradiation (EUV), and X ray.

Resist materials for use with these types of exposure light sourcesrequire lithography properties such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these conditions, a chemicallyamplified composition is used, which includes a base material componentthat exhibits a changed solubility in a developing solution under theaction of acid and an acid-generator component that generates acid uponexposure. For example, in the case where the developing solution is analkali developing solution (alkali developing process), a chemicallyamplified positive resist which contains, as a base component (baseresin), a resin which exhibits increased solubility in an alkalideveloping solution under action of acid, and an acid generator istypically used. If a resist film formed using such a resist compositionis selectively exposed at the time of forming a resist pattern, inexposed areas, an acid is generated from the acid generator component,and the polarity of the base resin increases by the action of thegenerated acid, thereby making the exposed areas soluble in the alkalideveloping solution. Thus, by conducting alkali developing, theunexposed portions remain to form a positive resist pattern. On theother hand, in the case of applying a solvent developing process using adeveloping solution containing an organic solvent (organic developingsolution), when the polarity of the base resin increases, the solubilityin the organic developing solution is relatively decreased. Therefore,unexposed areas of the resist film are dissolved in and removed by theorganic developing solution, whereby a negative-type resist pattern inwhich exposed areas remain as a pattern is formed. Such a solventdeveloping process for forming a negative-tone resist composition issometimes referred to as “negative-tone developing process” (PatentLiterature 1).

Currently, resins that contain structural units derived from(meth)acrylate esters within the main chain (acrylic resins) are nowwidely used as base resins for resist compositions that use ArF excimerlaser lithography, as they exhibit excellent transparency in thevicinity of 193 nm (for example, see Patent Document 2).

On the other hand, as acid generators usable in a chemically amplifiedresist composition, various types have been proposed including, forexample, onium salt acid generators; oxime sulfonate acid generators;diazomethane acid generators; nitrobenzylsulfonate acid generators;iminosulfonate acid generators; and disulfone acid generators. In recentyears, there has been proposed a photoacid generator using afluorine-containing sulfonic acid group-containing compound. (Forexample, Patent Literature 3)

DOCUMENTS OF RELATED ART Patent Literature

-   [Patent Literature 1] Japanese Unexamined Patent Application, First    Publication No. 2009-025723-   [Patent Document 2] Japanese Unexamined Patent Application, First    Publication No. 2003-241385-   [Patent Document 3] Japanese Unexamined Patent Application, First    Publication No. 2009-7327

SUMMARY OF THE INVENTION

As further progress is made in lithography techniques andminiaturization of resist patterns, improvement in resist materials hasbeen demanded in terms of various lithography properties.

However, when a conventional acid generator as that disclosed in PatentLiterature 3 was used, there was still room for improvement in variouslithography properties.

The present invention takes the above circumstances into consideration,with an object of providing a resist composition containing a compoundwhich is useful for acid generation in a resist composition, a methodfor forming a resist pattern using the resist composition, and acompound which is useful for acid generation in a resist composition.

A first aspect of the present invention is a resist compositionincluding a compound (m0) shown below.

In formula (m0), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group which may have asubstituent, an alkyl group which may have a substituent or an alkenylgroup which may have a substituent, provided that Rb² and Rb³ may bemutually bonded to form a ring with the sulfur atom; and X0⁻ representsa monovalent counteranion.

A second aspect of the present invention is a compound (B11) shownbelow.

In formula (B11), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group, an alkyl group or analkenyl group, provided that Rb² and Rb³ may be mutually bonded to forma ring with the sulfur atom; and X11⁻ is a counteranion represented byany one of formulae (b11-1) to (b11-3).

In formulae (b11-1) to (b11-3), Rb¹⁰¹, Rb¹⁰⁴ and Rb¹⁰⁵ eachindependently represents a cyclic group which may have a substituent ora chain-like alkenyl group which may have a substituent; Rb¹⁰⁶ to Rb¹⁰⁸each independently represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent; provided thatRb¹⁰⁴ and Rb¹⁰⁵ may be mutually bonded to form a ring; Rb¹⁰⁶ and Rb¹⁰⁷may be mutually bonded to form a ring; Rb¹⁰² represents a fluorine atomor a fluorinated alkyl group of 1 to 5 carbon atoms; Yb¹⁰¹ represents asingle bond or a divalent linking group containing an oxygen atom; Vb¹⁰¹to Vb¹⁰³ each independently represents a single bond, an alkylene groupor a fluorinated alkylene group; L¹⁰¹ and L¹⁰² each independentlyrepresents a single bond or an oxygen atom; Lb¹⁰³ to Lb¹⁰⁵ eachindependently represents a single bond, —CO— or —SO₂—.

A third aspect of the present invention is a polymeric compound (A0-B11)including a structural unit derived from a compound (B11-01) shownbelow.

In formula (B11-01), Rb¹ represents an electron withdrawing group; Rb²and Rb³ each independently represents an aryl group, an alkyl group oran alkenyl group, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X11-1⁻ is a counteranionrepresented by any one of formulae (b11-01-1) to (b11-01-3).

In formulae (b11-01-1) to (b11-01-3),

Rb²⁰¹ represents a chain-like alkenyl group which may have asubstituent;

Rb²⁰⁴ and Rb²⁰⁵ each independently represents a cyclic group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent (provided that at least one of Rb²⁰⁴ and Rb²⁰⁵ represents achain-like alkenyl group which may have a substituent);

Rb²⁰⁶ to Rb²⁰⁸ each independently represents a cyclic group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent(provided that at least one of Rb²⁰⁶ to Rb²⁰⁸-represents a chain-likealkenyl group which may have a substituent);

Rb¹⁰² represents a fluorine atom or a fluorinated alkyl group of 1 to 5carbon atoms; Yb¹⁰¹ represents a single bond or a divalent linking groupcontaining an oxygen atom; Vb¹⁰¹ to Vb¹⁰³ each independently representsa single bond, an alkylene group or a fluorinated alkylene group; L¹⁰¹and L¹⁰² each independently represents a single bond or an oxygen atom;Lb¹⁰³ and Lb¹⁰⁵ each independently represents a single bond, —CO— or—SO₂—.

A fourth aspect of the present invention is a resist compositionincluding the polymeric compound (A0-B11).

A fifth aspect of the present invention is a compound (D11) shown below.

In formula (D11), Rb₁ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group, an alkyl group or analkenyl group, provided that Rb² and Rb³ may be mutually bonded to forma ring with the sulfur atom; and X21⁻ is a counteranion represented byany one of formulae (d11-1) to (d11-3).

In formula (d11-1), Rd¹⁰ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent;

In formula (d11-2), Rd²⁰ represents a chain-like alkenyl group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or an aliphatic cyclic group which may have a substituent(provided that 10-camphorsulfonate is excluded from formula (d11-2));

in formula (d11-3), Rd³⁰ and Rd⁴⁰ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent;

provided that, the carbon atom adjacent to the S atom within the Rd²⁰group in formula (d11-2) has no fluorine atom bonded thereto; Yd¹⁰represents a single bond or a divalent linking group.

A sixth aspect of the present invention is a polymeric compound (A0-D11)including a structural unit derived from a compound (D11-01) shownbelow.

In formula (D11-01), Rb₁ represents an electron withdrawing group; Rb²and Rb³ each independently represents an aryl group, an alkyl group oran alkenyl group, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X21-1⁻ is a counteranionrepresented by any one of formulae (d11-01-1) to (d11-01-3);

in formula (d11-01-1), Rd¹⁰⁰ represents a chain-like alkenyl group whichmay have a substituent;

in formula (d11-01-2), Rd²⁰⁰ represents a chain-like alkenyl group whichmay have a substituent;

in formula (d11-01-3), at least one of Rd³⁰⁰ and Rd⁴⁰⁰ represents achain-like alkenyl group which may have a substituent;

provided that, the carbon atom adjacent to the S atom within the Rd²⁰⁰group in formula (d11-01-2) has no fluorine atom bonded thereto; Yd¹⁰represents a single bond or a divalent linking group.

A seventh aspect of the present invention is a resist compositionincluding the polymeric compound (A0-D11).

An eighth aspect of the present invention is a method of forming aresist pattern, including: using a resist composition of the firstaspect to form a resist film on a substrate; exposing of the resistfilm; and developing the resist film to form a resist pattern.

According to the present invention, there are provided a resistcomposition containing a compound which is useful for acid generation ina resist composition, a method for forming a resist pattern using theresist composition, and a compound which is useful for acid generationin a resist composition.

DETAILED DESCRIPTION OF THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group within an alkoxy group.

A “halogenated alkyl group” is a group in which part or all of thehydrogen atoms of an alkyl group is substituted with a halogen atom.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

A “fluorinated alkyl group” or a “fluorinated alkylene group” is a groupin which part or all of the hydrogen atoms of an alkyl group or analkylene group have been substituted with a fluorine atom.

The term “structural unit” refers to a monomer unit that contributes tothe formation of a polymeric compound (resin, polymer, copolymer).

A “structural unit derived from an acrylate ester” refers to astructural unit that is formed by the cleavage of the ethylenic doublebond of an acrylate ester.

An “acrylate ester” refers to a compound in which the terminal hydrogenatom of the carboxy group of acrylic acid (CH₂═CH—COOH) has beensubstituted with an organic group.

The acrylate ester may have the hydrogen atom bonded to the carbon atomon the α-position substituted with a substituent. The substituent(R^(α)) with which the hydrogen atom bonded to the carbon atom at theα-position is substituted is an atom other than the hydrogen atom or agroup, and examples thereof include an alkyl group having from 1 to 5carbon atoms, a halogenated alkyl group having from 1 to 5 carbon atoms,and a hydroxyalkyl group. A carbon atom on the α-position of an acrylateester refers to the carbon atom bonded to the carbonyl group, unlessspecified otherwise.

Hereafter, an acrylate ester having the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent issometimes referred to as “α-substituted acrylate ester”. Further,acrylate esters and α-substituted acrylate esters are collectivelyreferred to as “(α-substituted) acrylate ester”.

A “structural unit derived from hydroxystyrene or a hydroxystyrenederivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of hydroxystyrene or a hydroxystyrenederivative.

The term “hydroxystyrene derivative” includes compounds in which thehydrogen atom at the α-position of hydroxystyrene has been substitutedwith another substituent such as an alkyl group or a halogenated alkylgroup; and derivatives thereof. Examples of the derivatives thereofinclude hydroxystyrene in which the hydrogen atom of the hydroxy grouphas been substituted with an organic group and may have the hydrogenatom on the α-position substituted with a substituent; andhydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof hydroxystyrene, the same substituents as those described above forthe substituent on the α-position of the aforementioned α-substitutedacrylate ester can be mentioned.

A “structural unit derived from vinylbenzoic acid or a vinylbenzoic acidderivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acidderivative.

The term “vinylbenzoic acid derivative” includes compounds in which thehydrogen atom at the α-position of vinylbenzoic acid has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group; and derivatives thereof. Examples of thederivatives thereof include benzoic acid in which the hydrogen atom ofthe carboxy group has been substituted with an organic group and mayhave the hydrogen atom on the α-position substituted with a substituent;and benzoic acid which has a substituent other than a hydroxy group anda carboxy group bonded to the benzene ring and may have the hydrogenatom on the α-position substituted with a substituent. Here, theα-position (carbon atom on the α-position) refers to the carbon atomhaving the benzene ring bonded thereto, unless specified otherwise.

The term “styrene” is a concept including styrene and compounds in whichthe hydrogen atom at the α-position of styrene is substituted with othersubstituent such as an alkyl group and a halogenated alkyl group.

A “structural unit derived from styrene” or “structural unit derivedfrom a styrene derivative” refers to a structural unit that is formed bythe cleavage of the ethylenic double bond of styrene or a styrenederivative.

As the alkyl group as a substituent on the α-position, a linear orbranched alkyl group is preferable, and specific examples include alkylgroups of 1 to 5 carbon atoms, such as a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup.

Specific examples of the halogenated alkyl group as the substituent onthe α-position include groups in which part or all of the hydrogen atomsof the aforementioned “alkyl group as the substituent on the α-position”are substituted with halogen atoms. Examples of the halogen atom includea fluorine atom, a chlorine atom, a bromine atom and an iodine atom, anda fluorine atom is particularly desirable.

Specific examples of the hydroxyalkyl group as the substituent on theα-position include groups in which part or all of the hydrogen atoms ofthe aforementioned “alkyl group as the substituent on the α-position”are substituted with a hydroxy group. The number of hydroxy groupswithin the hydroxyalkyl group is preferably 1 to 5, and most preferably1.

The case of describing “may have a substituent” includes both of thecase where the hydrogen atom (—H) is substituted with a monovalent groupand the case where the methylene group (—CH₂—) is substituted with adivalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

<<Resist Composition>> <First Resist Composition>

A first resist composition according to the present embodiment includesa compound (m0) represented by general formula (m0).

The resist composition of the present invention preferably includes abase component (A) (hereafter, referred to as “component (A)”) whichexhibits changed solubility in a developing solution under action ofacid, an acid-generator component (B) (hereafter, referred to as“component (B)”) which generates acid upon exposure, and an aciddiffusion control agent component (hereafter, referred to as “component(D)”). When a resist film is formed using the resist composition and theformed resist film is subjected to a selective exposure, acid isgenerated from the component (B) at exposed portions, and the generatedacid acts on the component (A) to change the solubility of the component(A) in a developing solution, whereas the solubility of the component(A) in a developing solution is not changed at unexposed portions,thereby generating difference in solubility in a developing solutionbetween exposed portions and unexposed portions. Therefore, bysubjecting the resist film to development, the exposed portions aredissolved and removed to form a positive-tone resist pattern in the caseof a positive resist, whereas the unexposed portions are dissolved andremoved to form a negative-tone resist pattern in the case of a negativeresist. The component (D) functions as an acid diffusion control agent,i.e., a quencher which traps the acid generated from the component (B)and the like upon exposure.

The components (A), (B) and (D) which are preferably included in theresist composition of the present invention will be described later.

In the present specification, a resist composition which forms apositive resist pattern by dissolving and removing the exposed portionsis called a positive resist composition, and a resist composition whichforms a negative resist pattern by dissolving and removing the unexposedportions is called a negative resist composition.

The resist composition of the present invention may be either a positiveresist composition or a negative resist composition.

Further, in the formation of a resist pattern, the resist composition ofthe present invention can be applied to an alkali developing processusing an alkali developing solution in the developing treatment, or asolvent developing process using a developing solution containing anorganic solvent (organic developing solution) in the developingtreatment.

[Compound (m0)]

The resist composition of the present invention includes the compound(m0) shown below.

In formula (m0), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group which may have asubstituent, an alkyl group which may have a substituent or an alkenylgroup which may have a substituent, provided that Rb² and Rb³ may bemutually bonded to form a ring with the sulfur atom; and X0⁻ representsa monovalent counteranion.

In formula (m0), Rb¹ represents an electron withdrawing group.

In the present invention, the electron withdrawing group for Rb¹ refersto a substituent in which the Hammett substituent constant σ_(m) is apositive number. The Hammett σ_(m) value is described, for example, inorganic synthetic chemistry vol. 23, No. 8, (1965) p 631-642, written byYuho Tsuno, and Organic Chemistry, 4th Edition (Pine, Stanley H.;Hendrickson, James B.; Cram, Donald J.; Hammond, George S.) p. 656. Inthe present invention, although the electron withdrawing group isdefined by the σ_(m) value, the electron withdrawing group is notparticularly limited to substituents having a known value described inthe above literatures.

Examples of electron withdrawing group in which the σ_(m) value is apositive value include an alkoxy group {e.g., a methoxy group (σ_(m)value: 0.12)}, a hydroxy group (0.12), a halogen atom {e.g., a fluorineatom (0.34), a chlorine atom (0.37), a bromine atom (0.39), an iodineatom (0.35)}, a halogenated alkyl group {e.g., a trifluoromethyl group(0.43)}, an acyloxy group {e.g., an acetoxy group (0.37)}, an acyl group{for example, an acetyl group (0.38)}, a cyano group (0.56), a nitrogroup (0.71), and a sulfonyl group {e.g., a methylsulfonyl group(0.60)}.

As the electron withdrawing group, examples of the alkoxy group includea methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxygroup, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, ann-pentoxy group, an iso-pentoxy group, an neo-pentoxy group and a2-methylbutoxy group.

Examples of the acyl group include an acetyl group, an ethanoyl group, apropanoyl group, a butanoyl group, a pivaloyl group and a benzoyl group.

Examples of the halogenated alkyl group include a fluoroalkyl group inwhich part or all of the hydrogen atoms within the alkyl group has beensubstituted with a fluorine atom. Examples of the alkyl group include alinear alkyl group (a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group and an octyl group), a branched alkyl group(an isopropyl group, an isobutyl group, a sec-butyl group and atert-butyl group) and a cycloalkyl group (a cyclopropyl group, acyclobutyl group, a cyclopentyl group and a cyclohexyl group).

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

As the electron withdrawing group, examples of the acyloxy group includean acetoxy group, a butanoyloxy group and a benzoyloxy group.

Examples of the sulfonyl group include a methanesulfonyl group, abenzenesulfonyl group, a toluenesulfonyl group, atrifluoromethanesulfonyl group and a difluoromethanesulfonyl group.

Rb¹ is preferably a perfluoroalkyl group of 1 to 4 carbon atoms, a nitrogroup, a hydroxy group, a cyano group, an acyl group of 1 to 4 carbonatoms or a halogen atom, more preferably a perfluoroalkyl group of 1 to4 carbon atoms or a halogen atom, and most preferably a trifluoromethylgroup or a fluorine atom. When Rb¹ is in the above-mentioned range, thephotosensitivity and the solubility of the sulfonium salt becomesexcellent.

In formula (m0), Rb² and Rb³ each independently represents an aryl groupwhich may have a substituent, an alkyl group which may have asubstituent or an alkenyl group which may have a substituent, providedthat Rb² and Rb³ may be mutually bonded to form a ring with the sulfuratom.

Examples of the aryl group for Rb² and Rb³ include an unsubstituted arylgroup of 6 to 20 carbon atoms, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group for Rb² and Rb³, a chain-like or cyclic alkyl grouphaving 1 to 30 carbon atoms is preferable.

The alkenyl group for Rb² and Rb³ preferably has 2 to 10 carbon atoms.Specific examples of the substituent for Rb² and Rb³ include an alkylgroup, a halogen atom, a halogenated alkyl group, a carbonyl group, acyano group, an amino group, an aryl group, an arylthio group and groupsrepresented by formulae (ca-r-1) to (ca-r-7) described later.

Examples of the arylthio group as the substituent include a phenylthiogroup and a biphenylthio group.

When Rb² and Rb³ are mutually bonded to form a ring with the sulfuratom, Rb² and Rb³ may be bonded via a hetero atom such as a sulfur atom,an oxygen atom or a nitrogen atom or a functional group such as acarbonyl group, —SO—, —SO₂—, —SO₃—, —COO—, —CONH— or —N(R_(N))— (R_(N)represents an alkyl group of 1 to 5 carbon atoms).

The ring containing the sulfur atom in the skeleton thereof ispreferably a 3 to 10-membered ring, and most preferably a 5 to7-membered ring. Specific examples of the ring formed include athiophene ring, a thiazole ring, a benzothiophene ring, a thianthrenering, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthenering, a thioxanthone ring, a phenoxathiin ring, a tetrahydrothiopheniumring, and a tetrahydrothiopyranium ring.

Specific examples of the cation moiety of the compound represented bygeneral formula (m0) are shown below.

In general formula (m0), X0⁻ represents a monovalent counteranion.Examples of the monovalent counteranion include a sulfonate anion, acarboxylate anion, an imide anion, a methide anion, a carboanion, aborate anion, a halogen anion, a phosphate anion, an antimonate anionand an arsenate anion.

For example, the same anions as those defined for the anion in generalformulae (b-1) to (b-3) and (d1-1) to (d1-3) described later can bementioned.

In the first resist composition of the present embodiment, the amount ofthe compound (m0) is not particularly limited, and can be appropriatelyadjusted depending on the desired properties of the resist composition.

(Second Resist Composition)

A second resist composition of the present embodiment is a resistcomposition including a base component (A) which exhibits changedsolubility in a developing solution under action of acid and an acidgenerator component (B0) which generates acid upon exposure, the acidgenerator component (B0) preferably including a compound (B0-1)represented by general formula (b0) shown below.

In formula (b0), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group, an alkyl group or analkenyl group, provided that Rb² and Rb³ may be mutually bonded to forma ring with the sulfur atom; and X1⁻ represents a monovalentcounteranion capable of generating a strong acid.

<Component (A)>

In the present invention, the term “base component” refers to an organiccompound capable of forming a film, and is preferably an organiccompound having a molecular weight of 500 or more. When the organiccompound has a molecular weight of 500 or more, the film-forming abilityis improved, and a resist pattern of nano level can be easily formed.

The organic compound used as the base component is broadly classifiedinto non-polymers and polymers.

In general, as a non-polymer, any of those which have a molecular weightin the range of 500 to less than 4,000 is used. Hereafter, a “lowmolecular weight compound” refers to a non-polymer having a molecularweight in the range of 500 to less than 4,000.

As a polymer, any of those which have a molecular weight of 1,000 ormore is generally used. Hereafter, a “resin” refers to a polymer havinga molecular weight of 1,000 or more.

As the molecular weight of the polymer, the weight average molecularweight in terms of the polystyrene equivalent value determined by gelpermeation chromatography (GPC) is used.

As the component (A′), a resin, a low molecular weight compound, or acombination thereof may be used.

The component (A) may be a resin that exhibits increased solubility in adeveloping solution under action of acid or a resin that exhibitsdecreased solubility in a developing solution under action of acid.

In the present invention, the component (A) may be a component thatgenerates acid upon exposure.

In the present invention, the base component (A) preferably contains aresin component (A1) having a structural unit (a1) containing an aciddecomposable group that exhibits increased polarity by the action ofacid, a structural unit (a2) containing a lactone-containing cyclicgroup, a carbonate-containing cyclic group or an —SO₂— containing cyclicgroup, a structural unit (a3) containing a polar group-containingaliphatic hydrocarbon group and/or a structural unit (a4) containing anacid non-dissociable cyclic group.

(Structural Unit (a1))

The structural unit (a1) is a structural unit containing an aciddecomposable group that exhibits increased polarity by the action ofacid.

The term “acid decomposable group” refers to a group in which at least apart of the bond within the structure thereof is cleaved by the actionof an acid.

Examples of acid decomposable groups which exhibit increased polarity bythe action of an acid include groups which are decomposed by the actionof an acid to form a polar group.

Examples of the polar group include a carboxy group, a hydroxy group, anamino group and a sulfo group (—SO₃H). Among these, a polar groupcontaining —OH in the structure thereof (hereafter, referred to as“OH-containing polar group”) is preferable, a carboxy group or a hydroxygroup is more preferable, and a carboxy group is particularly desirable.

More specifically, as an example of an acid decomposable group, a groupin which the aforementioned polar group has been protected with an aciddissociable group (such as a group in which the hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup) can be given.

The “acid dissociable group” refers to both (i) a group in which thebond between the acid dissociable group and the adjacent atom is cleavedby the action of acid; and (ii) a group in which one of the bonds iscleaved by the action of acid, and then a decarboxylation reactionoccurs, thereby cleaving the bond between the acid dissociable group andthe adjacent atom.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, when the acid dissociable group is dissociated by theaction of acid, a polar group exhibiting a higher polarity than that ofthe acid dissociable group is generated, thereby increasing thepolarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, the solubility in an alkalideveloping solution changes and, the solubility in an organic developingsolution is relatively decreased.

The acid dissociable group is not particularly limited, and any of thegroups that have been conventionally proposed as acid dissociable groupsfor the base resins of chemically amplified resists can be used.

Examples of the acid dissociable group for protecting the carboxy groupor hydroxy group as a polar group include the acid dissociable grouprepresented by general formula (a1-r-1) shown below (hereafter, for thesake of convenience, sometimes referred to as “acetal-type aciddissociable group”).

In the formula, Ra′¹ and Ra′² represents a hydrogen atom or an alkylgroup; and Ra′³ represents a hydrocarbon group, provided that Ra′³ maybe bonded to Ra′¹ or Ra′².

In formula (a1-r-1), as the lower alkyl group for Ra′¹ and Ra′², thesame lower alkyl groups as those described above the alkyl groups as thesubstituent which may be bonded to the carbon atom on the α-position ofthe aforementioned α-substituted alkylester can be used, although amethyl group or ethyl group is preferable, and a methyl group isparticularly desirable.

The hydrocarbon group for Ra′³ is preferably an alkyl group of 1 to 20carbon atoms, more preferably an alkyl group of 1 to 10 carbon atoms,and still more preferably a linear or branched alkyl group. Specificexamples thereof include a methyl group, an ethyl group, a propyl group,an isopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group, a neopentyl group, a1,1-dimethylethyl group, a 1,1-diethylpropyl group, a 2,2-dimethylpropylgroup and a 2,2-dimethylbutyl group.

In the case where Ra′³ represents a cyclic hydrocarbon group, the cyclichydrocarbon group may be aliphatic or aromatic, and may be polycyclic ormonocyclic. As the monocyclic aliphatic hydrocarbon group, a group inwhich 1 hydrogen atom has been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 8 carbon atoms, andspecific examples thereof include cyclopentane, cyclohexane andcyclooctane. As the polycyclic group, a group in which 1 hydrogen atomhas been removed from a polycycloalkane is preferable, and thepolycyclic group preferably has 7 to 12 carbon atoms. Examples of thepolycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

In the case where the hydrocarbon group is an aromatic hydrocarbongroup, examples of the aromatic ring contained in the aromatichydrocarbon group include aromatic hydrocarbon rings, such as benzene,biphenyl, fluorene, naphthalene, anthracene and phenanthrene; andaromatic hetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich 1 hydrogen atom has been removed from the aforementioned aromatichydrocarbon ring (aryl group); and a group in which 1 hydrogen atom ofthe aforementioned aryl group has been substituted with an alkylenegroup (an arylalkyl group such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup or a 2-naphthylethyl group). The alkylene group (alkyl chainwithin the arylalkyl group) preferably has 1 to 4 carbon atom, morepreferably 1 or 2, and most preferably 1.

In the case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4 to 7-membered ring, and more preferably a4 to 6-membered ring. Specific examples of the cyclic group includetetrahydropyranyl group and tetrahydrofuranyl group.

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented bygeneral formula (a1-r-2) shown below (hereafter, with respect to theacid dissociable group represented by the following formula (a1-r-2),the acid dissociable group constituted of alkyl groups is referred to as“tertiary ester-type acid dissociable group”).

In the formula, Ra′⁴ to Ra′⁶ each independently represents a hydrocarbongroup, provided that Ra′⁵ and Ra′⁶ may be mutually bonded to form aring.

As the hydrocarbon group for Ra′⁴ to Ra′⁶, the same groups as thosedescribed above for Ra′³ can be mentioned. Ra′⁴ is preferably an alkylgroup having from 1 to 5 carbon atoms. In the case where Ra′⁵ and Ra′⁶are mutually bonded to form a ring, a group represented by generalformula (a1-r2-1) shown below can be mentioned.

On the other hand, in the case where Ra′⁴ to Ra′⁶ are not mutuallybonded and independently represent a hydrocarbon group, the grouprepresented by general formula (a1-r2-2) shown below can be mentioned.

In the formulae, Ra′¹⁰ represents an alkyl group of 1 to 10 carbonatoms; Ra′¹¹ is a group which forms an aliphatic cyclic group togetherwith a carbon atom having Ra′¹⁰ bonded thereto; and Ra′¹² to Ra′¹⁴ eachindependently represents a hydrocarbon group.

In the formula (a1-r2-1), as the alkyl group of 1 to 10 carbon atoms forRa′¹⁰, the same groups as described above for the linear or branchedalkyl group for Ra′³ in the formula (a1-r-1) are preferable. In theformula (a1-r2-1), as the aliphatic cyclic group which is formed byRa′¹¹, the same groups as those described above for the cyclic alkylgroup for Ra′³ in the formula (a1-r-1) are preferable.

In the formula (a1-r2-2), it is preferable that Ra′² and Ra′¹⁴ eachindependently represents an alkyl group or 1 to 10 carbon atoms, and itis more preferable that the alkyl group is the same group as thedescribed above for the linear or branched alkyl group for Ra′³ in theformula (a1-r-1), it is still more preferable that the alkyl group is alinear alkyl group of 1 to 5 carbon atoms, and it is particularlypreferable that the alkyl group is a methyl group or an ethyl group.

In the formula (a1-r2-2), it is preferable that Ra′¹³ is the same groupas described above for the linear, branched or cyclic alkyl group forRa′³ in the formula (a1-r-1).

Among these, the same cyclic alkyl group as those describe above forRa′³ is more preferable.

Specific examples of the formula (a1-r2-1) are shown below. In theformulae shown below, “*” represents a valence bond.

Specific examples of the formula (a1-r2-2) are shown below.

Examples of the acid dissociable group for protecting a hydroxy group asa polar group include the acid dissociable group represented by generalformula (a1-r-3) shown below (hereafter, referred to as “tertiaryalkyloxycarbonyl-type acid dissociable group”).

In the formula, Ra′⁷ to Ra′⁹ each independently represents an alkylgroup.

In the formula (a1-r-3), Ra′⁷ to Ra′⁹ is preferably an alkyl group of 1to 5 carbon atoms, and more preferably an alkyl group of 1 to 3 carbonatoms.

Further, the total number of carbon atoms within the alkyl group ispreferably 3 to 7, more preferably 3 to 5, and most preferably 3 or 4.

Examples of the structural unit (a1) include a structural unit derivedfrom an acrylate ester which may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent andcontains an acid decomposable group which exhibits increased polarity bythe action of acid; a structural unit derived from hydroxystyrene or ahydroxystyrene derivative in which at least a part of the hydrogen atomof the hydroxy group is protected with a substituent containing an aciddecomposable group; and a structural unit derived from vinylbenzoic acidor a vinylbenzoic acid derivative in which at least a part of thehydrogen atom within —C(═O)—OH is protected with a substituentcontaining an acid decomposable group.

As the structural unit (a1), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

As the structural unit (a1), structural units represented by generalformulae (a1-1) to (a1-3) shown below are preferable.

In the formulae, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Va¹represents a divalent hydrocarbon group which may have an ether bond, anurethane bond or an amide bond; n_(a1) represents an integer of 0 to 2;

Ra¹ represents an acid dissociable group represented by theaforementioned formula (a1-r-1) or (a1-r-2);

Wa¹ represents a hydrocarbon group having a valency of n_(a2)+1; n_(a2)represents an integer of 1 to 3;

Ra² represents an acid dissociable group represented by theaforementioned formula (a1-r-1) or (a1-r-3);

Wa² represents a hydrocarbon group having a valency of n_(a3)+1; n_(a3)represents an integer of 1 to 3;

Va² represents a divalent hydrocarbon group which may have an etherbond, an urethane bond or an amide bond;

and Ra³ represents an acid dissociable group represented by theaforementioned formula (a1-r-1) or (a1-r-2).

In general formulae (a1-1) to (a1-3), as the alkyl group of 1 to 5carbon atoms for R, a linear or branched alkyl group of 1 to 5 carbonatoms is preferable, and specific examples thereof include a methylgroup, an ethyl group, a propyl group, an isopropyl group, an n-butylgroup, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group. The halogenated alkyl group of 1to 5 carbon atoms represented by R is a group in which part or all ofthe hydrogen atoms of the aforementioned alkyl group of 1 to 5 carbonatoms have been substituted with halogen atoms. Examples of the halogenatom include a fluorine atom, a chlorine atom, a bromine atom and aniodine atom, and a fluorine atom is particularly desirable.

As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In general formula (a1-1), the hydrocarbon group for Va¹ may be eitheran aliphatic hydrocarbon group or an aromatic hydrocarbon group. An“aliphatic hydrocarbon group” refers to a hydrocarbon group that has noaromaticity. The aliphatic hydrocarbon group as the divalent hydrocarbongroup for Va¹ may be either saturated or unsaturated. In general, thealiphatic hydrocarbon group is preferably saturated.

As specific examples of the aliphatic hydrocarbon group, a linear orbranched aliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

Further, as the group for Va¹, a group in which the aforementioneddivalent hydrocarbon group has been bonded via an ether bond, urethanebond or amide bond can be mentioned.

The linear or branched aliphatic hydrocarbon group preferably has 1 to10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4,and most preferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which two hydrogenatoms have been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given. As the linear orbranched aliphatic hydrocarbon group, the same groups as those describedabove can be used.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a monocyclic group or apolycyclic group. As the monocyclic aliphatic hydrocarbon group, a groupin which 2 hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic group, a group in which two hydrogen atoms have been removedfrom a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The aromatic hydrocarbon group is a hydrocarbon group having an aromaticring.

The aromatic hydrocarbon group as the divalent hydrocarbon group for Va¹preferably has 3 to 30 carbon atoms, more preferably 5 to 30, still morepreferably 5 to 20, still more preferably 6 to 15, and most preferably 6to 10. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic hydrocarbongroup.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup include aromatic hydrocarbon rings, such as benzene, biphenyl,fluorene, naphthalene, anthracene and phenanthrene; and aromatic heterorings in which part of the carbon atoms constituting the aforementionedaromatic hydrocarbon rings has been substituted with a hetero atom.Examples of the hetero atom within the aromatic hetero rings include anoxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring (arylene group); and a group in which onehydrogen atom has been removed from the aforementioned aromatichydrocarbon ring (aryl group) and one hydrogen atom has been substitutedwith an alkylene group (such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup, or a 2-naphthylethyl group). The alkylene group (alkyl chainwithin the arylalkyl group) preferably has 1 to 4 carbon atom, morepreferably 1 or 2, and most preferably 1.

In the aforementioned formula (a1-2), the hydrocarbon group for Wa¹having a valency of n_(a2)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic cyclic grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof. As the specific examplesthereof, the same groups as those described above for Va¹ in theaforementioned formula (a1-1) can be mentioned.

The valency of n_(a2)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

In the aforementioned formula (a1-3), the hydrocarbon group for Wa²having a valency of n_(a3)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic cyclic grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof. As the specific examplesthereof, the same groups as those described above for Va¹ in theaforementioned formula (a1-1) can be mentioned.

The valency of n_(a3)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

In formula (a1-3), examples of Va² are the same as defined for thegroups for Va¹ in formula (a1-1).

As the structural unit (a1-2), a structural unit represented by generalformula (a1-2-01) shown below is particularly desirable.

In the formula (a1-2-01), Ra² represents an acid dissociable grouprepresented by the aforementioned formula (a1-r-1) or (a1-r-3); n_(a2)is an integer of 1 to 3, preferably 1 or 2, and more preferably 1; c isan integer of 0 to 3, preferably 0 or 1, and more preferably 1; R is thesame as defined above.

Specific examples of the structural units (a1-1) and (a1-2) are shownbelow. In the formulae shown below, R^(α) represents a hydrogen atom, amethyl group or a trifluoromethyl group.

In the component (A), the amount of the structural unit (a1) based onthe combined total of all structural units constituting the component(A) is preferably 20 to 80 mol %, more preferably 20 to 75 mol %, andstill more preferably 25 to 70 mol %. By ensuring the lower limit,various lithography properties such as sensitivity, resolution and LWRare improved. On the other hand, when the amount of the structural unit(a1) is no more than the upper limit of the above-mentioned range, agood balance can be achieved with the other structural units.

(Structural Unit (a2))

The structural unit (a2) is a structural unit containing alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group.

When the component (A1) is used for forming a resist film, thestructural unit (a2) containing a lactone-containing cyclic group or acarbonate-containing cyclic group is effective in improving the adhesionbetween the resist film and the substrate.

The aforementioned structural unit (a1) which contains alactone-containing cyclic group or a carbonate-containing cyclic groupfalls under the definition of the structural unit (a2); however, such astructural unit is regarded as a structural unit (a1), and does not fallunder the definition of the structural unit (a2).

When the component (A1) is used for forming a resist film, thestructural unit (a2) containing an —SO₂— containing cyclic group iseffective in improving the adhesion between the resist film and thesubstrate.

The aforementioned structural unit (a1) which contains an —SO₂—containing cyclic group falls under the definition of the structuralunit (a2); however, such a structural unit is regarded as a structuralunit (a1), and does not fall under the definition of the structural unit(a2).

The structural unit (a2) is preferably a structural unit represented bygeneral formula (a2-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms, a halogenated alkyl group of 1 to 5 carbon atoms, ahydroxyalkyl group, an alkoxy group; Ya²¹ represents a single bond or adivalent linking group; La²¹ represents —O—, —COO— or —OCO—; and R′represents a hydrogen atom or a methyl group, provided that, when La²¹represents —O—, Ya²¹¹ does not represents —CO—; and Ra²¹ represents alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group.

The divalent linking group for Ya²¹ is not particularly limited, andpreferable examples thereof include a divalent hydrocarbon group whichmay have a substituent and a divalent linking group containing a heteroatom.

(Divalent Hydrocarbon Group which May have a Substituent)

The hydrocarbon group as a divalent linking group may be either analiphatic hydrocarbon group or an aromatic hydrocarbon group.

An “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof. Specifically, groupsexemplified above for Va¹ in the aforementioned formula (a1-1) ca bementioned.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

As examples of the hydrocarbon group containing a ring in the structurethereof, a cyclic aliphatic hydrocarbon group containing a hetero atomin the ring structure thereof and may have a substituent (a group inwhich two hydrogen atoms have been removed from an aliphatic hydrocarbonring), a group in which the cyclic aliphatic hydrocarbon group is bondedto the terminal of the aforementioned chain-like aliphatic hydrocarbongroup, and a group in which the cyclic aliphatic group is interposedwithin the aforementioned linear or branched aliphatic hydrocarbongroup, can be given. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

Specific examples of the cyclic aliphatic hydrocarbon group include thesame group as exemplified above for Va¹ in the aforementioned formula(a1-1).

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

The cyclic aliphatic hydrocarbon group may have part of the carbon atomsconstituting the ring structure thereof substituted with a substituentcontaining a hetero atom. As the substituent containing a hetero atom,—O—, —C(═O)—O—, —S—, —S(═O)₂— or —S(═O)₂—O— is preferable.

Specific examples of the aromatic hydrocarbon group as a divalenthydrocarbon group include the same group as exemplified above for Va¹ inthe aforementioned formula (a1-1).

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the cyclic aliphatichydrocarbon group can be used.

(Divalent Linking Group Containing a Hetero Atom)

With respect to a divalent linking group containing a hetero atom, ahetero atom is an atom other than carbon and hydrogen, and examplesthereof include an oxygen atom, a nitrogen atom, a sulfur atom and ahalogen atom.

In the case where Ya²¹ represents a divalent linking group containing ahetero atom, preferable examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (whereinH may be substituted with a substituent such as an alkyl group or anacyl group), —S—, —S(═O)₂—, —S(═O)₂—O—, a group represented by generalformula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—Y²²— [in the formulae, Y²¹ andY²² each independently represents a divalent hydrocarbon group which mayhave a substituent, and O represents an oxygen atom; and m′ representsan integer of 0 to 3.

The divalent linking group containing a hetero atom represents—C(═O)—NH—, —NH—, or —NH—C(═NH)—, H may be substituted with asubstituent such as an alkyl group, an acyl group or the like. Thesubstituent (an alkyl group, an acyl group or the like) preferably has 1to 10 carbon atoms, more preferably 1 to 8, and most preferably 1 to 5.

In formulae —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—,—C(═O)—O—Y²¹—[Y²¹—C(═O)—O]_(m′)—Y²²— and —Y²¹—O—C(═O)—Y²²—, Y²¹ and Y²²each independently represents a divalent hydrocarbon group which mayhave a substituent. Examples of the divalent hydrocarbon group includethe same groups as those described above as the “divalent hydrocarbongroup which may have a substituent” in the explanation of theaforementioned divalent linking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula —[Y²¹—C(═O)—O]_(m′)—Y²²—, m′represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and most preferably 1. Namely, it is particularlydesirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m′)—Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

In the present invention, Ya²¹ preferably represents an ester bond[—C(═O)—O-], an ether bond (—O—), a linear or branched alkylene group, acombination of these, or a single bond.

In formula (a2-1), Ra²¹ represents a lactone-containing cyclic group, acarbonate-containing cyclic group or an —SO₂— containing cyclic group.

The term “lactone-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)— structure (lactone ring). Theterm “lactone ring” refers to a single ring containing a —O—C(O)—structure, and this ring is counted as the first ring. Alactone-containing cyclic group in which the only ring structure is thelactone ring is referred to as a monocyclic group, and groups containingother ring structures are described as polycyclic groups regardless ofthe structure of the other rings. The lactone-containing cyclic groupmay be either a monocyclic group or a polycyclic group.

As the lactone-containing cyclic group, there is no particularlimitation, and an arbitrary group may be used.

Specific examples include groups represented by general formulas(a2-r-1) to (a2-r-7) shown below. Hereinbelow, “*” represents a valencebond.

In the formulae, each Ra′²¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; n′ represents aninteger of 0 to 2; and m′ represents 0 or 1.

In general formulae (a2-r-1) to (a2-r-7) above, A″ represents an oxygenatom (—O—), a sulfur atom (—S—) or an alkylene group of 1 to 5 carbonatoms which may contain an oxygen atom or a sulfur atom. As the alkylenegroup of 1 to 5 carbon atoms for A″, a linear or branched alkylene groupis preferable, and examples thereof include a methylene group, anethylene group, an n-propylene group and an isopropylene group.

Examples of alkylene groups that contain an oxygen atom or a sulfur atominclude the aforementioned alkylene groups in which —O— or —S— is bondedto the terminal of the alkylene group or present between the carbonatoms of the alkylene group. Specific examples of such alkylene groupsinclude —O—CH₂—, —CH₂—O—CH₂—, —S—CH₂— and —CH₂—S—CH₂—. As A″, analkylene group of 1 to 5 carbon atoms or —O— is preferable, morepreferably an alkylene group of 1 to 5 carbon atoms, and most preferablya methylene group.

In formulae (a2-r-1) to (a2-r-7), the alkyl group for Ra′²¹ ispreferably an alkyl group of 1 to 6 carbon atoms. Further, the alkylgroup is preferably a linear alkyl group or a branched alkyl group.Specific examples include a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, a neopentyl groupand a hexyl group. Among these, a methyl group or ethyl group ispreferable, and a methyl group is particularly desirable.

The alkoxy group for Ra′²¹ is preferably an alkoxy group of 1 to 6carbon atoms.

Further, the alkoxy group is preferably a linear or branched alkoxygroup. Specific examples of the alkoxy groups include the aforementionedalkyl groups for Ra′²¹ having an oxygen atom (—O—) bonded thereto.

As examples of the halogen atom for Ra′²¹, a fluorine atom, chlorineatom, bromine atom and iodine atom can be given. Among these, a fluorineatom is preferable.

Examples of the halogenated alkyl group for Ra′²¹ include groups inwhich part or all of the hydrogen atoms within the aforementioned alkylgroup for Ra′²¹ has been substituted with the aforementioned halogenatoms. As the halogenated alkyl group, a fluorinated alkyl group ispreferable, and a perfluoroalkyl group is particularly desirable.

With respect to —COOR″ and —OC(═O)R″ for Ra′²¹, R″ represents a hydrogenatom, an alkyl group, a lactone-containing cyclic group, acarbonate-containing cyclic group or an —SO₂— containing cyclic group.

The alkyl group for R″ may be linear, branched or cyclic, and preferablyhas 1 to 15 carbon atoms.

When R″ represents a linear or branched alkyl group, it is preferably analkyl group of 1 to 10 carbon atoms, more preferably an alkyl group of 1to 5 carbon atoms, and most preferably a methyl group or an ethyl group.

When R″ is a cyclic alkyl group (cycloalkyl group), it preferably has 3to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and mostpreferably 5 to 10 carbon atoms. Specific examples include groups inwhich one or more hydrogen atoms have been removed from amonocycloalkane or a polycycloalkane such as a bicycloalkane,tricycloalkane or tetracycloalkane which may or may not be substitutedwith a fluorine atom or a fluorinated alkyl group. Specific examplesinclude groups in which one or more hydrogen atoms have been removedfrom a monocycloalkane such as cyclopentane or cyclohexane; and groupsin which one or more hydrogen atoms have been removed from apolycycloalkane such as adamantane, norbornane, isobornane,tricyclodecane or tetracyclododecane.

Examples of the lactone-containing cyclic group for R″ include groupsrepresented by the aforementioned general formulae (a2-r-1) to (a2-r-7).

The carbonate-containing cyclic group for R″ is the same as defined forthe carbonate-containing cyclic group described later. Specific examplesof the carbonate-containing cyclic group include groups represented bygeneral formulae (ax3-r-1) to (ax3-r-3).

The —SO₂— containing cyclic group for R″ is the same as defined for the—SO₂— containing cyclic group described later. Specific examples of the—SO₂— containing cyclic group include groups represented by generalformulae (a5-r-1) to (a5-r-4).

The hydroxyalkyl group for Ra′²¹ preferably has 1 to 6 carbon atoms, andspecific examples thereof include the alkyl groups for Ra′²¹ in which atleast one hydrogen atom has been substituted with a hydroxy group.

In formulae (a2-r-2), (a2-r-3) and (a2-r-5), as the alkylene group of 1to 5 carbon atoms represented by A″, a linear or branched alkylene groupis preferable, and examples thereof include a methylene group, anethylene group, an n-propylene group and an isopropylene group. Examplesof alkylene groups that contain an oxygen atom or a sulfur atom includethe aforementioned alkylene groups in which —O— or —S— is bonded to theterminal of the alkylene group or present between the carbon atoms ofthe alkylene group. Specific examples of such alkylene groups include—O—CH₂—, —CH₂—O—CH₂—, —S—CH₂— and —CH₂—S—CH₂—. As A″, an alkylene groupof 1 to 5 carbon atoms or —O— is preferable, more preferably an alkylenegroup of 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups represented by the aforementionedgeneral formulae (a2-r-1) to (a2-r-7) are shown below.

An “—SO₂— containing cyclic group” refers to a cyclic group having aring containing —SO₂— within the ring structure thereof, i.e., a cyclicgroup in which the sulfur atom (S) within —SO₂— forms part of the ringskeleton of the cyclic group. The ring containing —SO₂— within the ringskeleton thereof is counted as the first ring. A cyclic group in whichthe only ring structure is the ring that contains —SO₂— in the ringskeleton thereof is referred to as a monocyclic group, and a groupcontaining other ring structures is described as a polycyclic groupregardless of the structure of the other rings. The —SO₂— containingcyclic group may be either a monocyclic group or a polycyclic group.

As the —SO₂— containing cyclic group for the cyclic hydrocarbon grouprepresented by R¹, a cyclic group containing —O—SO₂— within the ringskeleton thereof, i.e., a cyclic group containing a sultone ring inwhich —O—S— within the —O—SO₂— group forms part of the ring skeletonthereof is particularly desirable. Specific examples of the —SO₂—containing cyclic group include groups represented by general formulae(a5-r-1) to (a5-r-4) shown below.

In the formulae, each Ra′⁵¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; and n′ represents aninteger of 0 to 2.

In general formulae (a5-r-1) to (a5-r-4), A″ is the same as defined forA″ in general formulae (a2-r-1) to (a2-r-7). The alkyl group, alkoxygroup, halogen atom, halogenated alkyl group, —COOR″, —OC(═O)R″ andhydroxyalkyl group for Ra′⁵¹ are the same as defined for Ra′²¹ in theaforementioned general formulae (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulas (a5-r-1) to (a5-r-4) are shown below. In the formulaeshown below, “Ac” represents an acetyl group.

As the —SO₂— containing cyclic group, a group represented by theaforementioned general formula (a5-r-1) is preferable, at least onemember selected from the group consisting of groups represented by theaforementioned chemical formulas (r-sl-1-1), (r-sl-1-18), (r-sl-3-1) and(r-sl-4-1) is more preferable, and a group represented by chemicalformula (r-sl-1-1) is most preferable.

The term “carbonate-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)—O— structure (carbonate ring).The term “carbonate ring” refers to a single ring containing a—O—C(═O)—O— structure, and this ring is counted as the first ring. Acarbonate-containing cyclic group in which the only ring structure isthe carbonate ring is referred to as a monocyclic group, and groupscontaining other ring structures are described as polycyclic groupsregardless of the structure of the other rings. The carbonate-containingcyclic group may be either a monocyclic group or a polycyclic group.

The carbonate-containing cyclic group as the cyclic hydrocarbon groupfor R¹ is not particularly limited, and an arbitrary group may be used.Specific examples include groups represented by general formulas(ax3-r-1) to (ax3-r-3) shown below.

In the formulae, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group ora cyano group; R″ represents a hydrogen atom or an alkyl group; A″represents an oxygen atom, a sulfur atom or an alkylene group of 1 to 5carbon atoms which may contain an oxygen atom or a sulfur atom; p′represents an integer of 0 to 3; and q′ represents 0 or 1.

In general formulae (ax3-r-1) to (ax3-r-3), A″ is the same as definedfor A″ in general formula (a2-r-1).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′³¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (ax3-r-1) to (ax3-r-3) are shown below.

Among the above examples, a lactone-containing cyclic group or an —SO₂—containing cyclic group is preferable, a group represented by thegeneral formula (a2-r-1), (a2-r-2) or (a5-r-1) is more preferable, and agroup represented by any one of the chemical formulae (r-lc-1-1) to(r-lc-1-7), (r-lc-2-1) to (r-lc-2-13), (r-sl-1-1) and (r-sl-1-18) isstill more preferable.

As the structural unit (a2) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) contains the structural unit (a2), the amount ofthe structural unit (a2) based on the combined total of all structuralunits constituting the component (A1) is preferably 1 to 80 mol %, morepreferably 5 to 70 mol %, still more preferably 10 to 65 mol %, and mostpreferably 10 to 60 mol %. When the amount of the structural unit (a2)is at least as large as the lower limit of the above-mentioned range,the effect of using the structural unit (a2) can be satisfactorilyachieved. On the other hand, when the amount of the structural unit (a2)is no more than the upper limit of the above-mentioned range, a goodbalance can be achieved with the other structural units, and variouslithography properties such as DOF and CDU and pattern shape can beimproved.

(Structural Unit (a3))

The structural unit (a3) is a structural unit containing a polargroup-containing aliphatic hydrocarbon group (provided that thestructural units that fall under the definition of structural units (a1)and (a2) are excluded).

When the component (A1) includes the structural unit (a3), it ispresumed that the hydrophilicity of the component (A1) is enhanced,thereby contributing to improvement in resolution.

Examples of the polar group include a hydroxyl group, cyano group,carboxyl group, or hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms,although a hydroxyl group is particularly desirable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) of 1 to 10 carbon atoms,and cyclic aliphatic hydrocarbon groups (cyclic groups). These cyclicgroups can be selected appropriately from the multitude of groups thathave been proposed for the resins of resist compositions designed foruse with ArF excimer lasers. The cyclic group is preferably a polycyclicgroup, more preferably a polycyclic group of 7 to 30 carbon atoms.

Of the various possibilities, structural units derived from an acrylateester that include an aliphatic polycyclic group that contains ahydroxyl group, cyano group, carboxyl group or a hydroxyalkyl group inwhich part of the hydrogen atoms of the alkyl group have beensubstituted with fluorine atoms are particularly desirable. Examples ofthe polycyclic group include groups in which two or more hydrogen atomshave been removed from a bicycloalkane, tricycloalkane, tetracycloalkaneor the like. Specific examples include groups in which two or morehydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane. Of these polycyclic groups, groups in which two ormore hydrogen atoms have been removed from adamantane, norbornane ortetracyclododecane are preferred industrially.

As the structural unit (a3), there is no particular limitation as longas it is a structural unit containing a polar group-containing aliphatichydrocarbon group, and an arbitrary structural unit may be used.

The structural unit (a3) is preferably a structural unit derived from anacrylate ester which may have the hydrogen atom bonded to the carbonatom on the α-position substituted with a substituent and contains apolar group-containing aliphatic hydrocarbon group.

When the aliphatic hydrocarbon group within the polar group-containingaliphatic hydrocarbon group is a linear or branched hydrocarbon group of1 to 10 carbon atoms, the structural unit (a3) is preferably astructural unit derived from a hydroxyethyl ester of acrylic acid. Onthe other hand, when the hydrocarbon group is a polycyclic group,structural units represented by formulas (a3-1), (a3-2) and (a3-3) shownbelow are preferable.

In the formulas, R is the same as defined above; j is an integer of 1 to3; k is an integer of 1 to 3; t′ is an integer of 1 to 3; 1 is aninteger of 1 to 5; and s is an integer of 1 to 3.

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When jis 2, it is preferable that the hydroxyl groups be bonded to the 3rd and5th positions of the adamantyl group. When j is 1, it is preferable thatthe hydroxyl group be bonded to the 3rd position of the adamantyl group.

j is preferably 1, and it is particularly desirable that the hydroxylgroup be bonded to the 3rd position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferablybonded to the 5th or 6th position of the norbomyl group.

In formula (a3-3), t′ is preferably 1. l is preferably 1. s ispreferably 1. Further, it is preferable that a 2-norbomyl group or3-norbornyl group be bonded to the terminal of the carboxy group of theacrylic acid. The fluorinated alkyl alcohol is preferably bonded to the5th or 6th position of the norbomyl group.

As the structural unit (a3) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

The amount of the structural unit (a3) within the component (A1) basedon the combined total of all structural units constituting the component(A1) is preferably 5 to 50 mol %, more preferably 5 to 40 mol %, andstill more preferably 5 to 25 mol %.

When the amount of the structural unit (a3) is at least as large as thelower limit of the above-mentioned range, the effect of using thestructural unit (a3) can be satisfactorily achieved. On the other hand,when the amount of the structural unit (a3) is no more than the upperlimit of the above-mentioned range, a good balance can be achieved withthe other structural units.

(Structural Unit (a4))

The structural unit (a4) is a structural unit containing an acidnon-dissociable cyclic group. When the component (A1) includes thestructural unit (a4), dry etching resistance of the resist pattern to beformed is improved. Further, the hydrophobicity of the component (A1) isfurther improved. Increase in the hydrophobicity contributes toimprovement in terms of resolution, shape of the resist pattern and thelike, particularly in an organic solvent developing process.

An “acid non-dissociable, aliphatic cyclic group” in the structural unit(a4) refers to a cyclic group which is not dissociated by the action ofacid generated from the component (B) described later upon exposure, andremains in the structural unit.

As the structural unit (a4), a structural unit which contains anon-acid-dissociable aliphatic cyclic group, and is also derived from anacrylate ester is preferable. Examples of this cyclic group include thesame groups as those described above in relation to the aforementionedstructural unit (a1), and any of the multitude of conventional groupsused within the resin component of resist compositions for ArF excimerlasers or KrF excimer lasers (and particularly for ArF excimer lasers)can be used.

In consideration of industrial availability and the like, at least onepolycyclic group selected from amongst a tricyclodecyl group, adamantylgroup, tetracyclododecyl group, isobornyl group, and norbornyl group isparticularly desirable. These polycyclic groups may be substituted witha linear or branched alkyl group of 1 to 5 carbon atoms.

Specific examples of the structural unit (a4) include units withstructures represented by general formulas (a4-1) to (a4-7) shown below.

In the formulae, R^(α) represents a hydrogen atom, a methyl group or atrifluoromethyl group.

As the structural unit (a4) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the structural unit (a4) is included in the component (A1), theamount of the structural unit (a4) based on the combined total of allthe structural units that constitute the component (A1) is preferablywithin the range from 1 to 30 mol %, and more preferably from 10 to 20mol %.

The component (A1) is preferably a copolymer containing the structuralunit (a1). The copolymer containing the structural unit (a1) ispreferably a copolymer further containing a structural unit (a2) or(a3), and still more preferably a copolymer containing the structuralunits (a1), (a2) and (a3).

In the present invention, the weight average molecular weight (Mw) (thepolystyrene equivalent value determined by gel permeationchromatography) of the component (A1) is not particularly limited, butis preferably 1,000 to 50,000, more preferably 1,500 to 30,000, and mostpreferably 2,000 to 20,000. When the weight average molecular weight isno more than the upper limit of the above-mentioned range, the resistcomposition exhibits a satisfactory solubility in a resist solvent. Onthe other hand, when the weight average molecular weight is at least aslarge as the lower limit of the above-mentioned range, dry etchingresistance and the cross-sectional shape of the resist pattern becomessatisfactory.

Further, the dispersity (Mw/Mn) of the component (A1) is notparticularly limited, but is preferably 1.0 to 5.0, more preferably 1.0to 3.0, and most preferably 1.2 to 2.5.

Here, Mn is the number average molecular weight.

As the component (A), one type may be used alone, or two or more typesmay be used in combination.

In the component (A), the amount of the component (A1) based on thetotal weight of the component (A) is preferably 25% by weight or more,more preferably 50% by weight or more, still more preferably 75% byweight or more, and may be even 100% by weight. When the amount of thecomponent (A1) is 25% by weight or more, various lithography propertiesare improved, such as improvement in MEF and circularity, and reductionof roughness.

In the resist composition of the present invention, as the component(A), one type may be used, or two or more types of compounds may be usedin combination.

In the resist composition of the present invention, the amount of thecomponent (A) can be appropriately adjusted depending on the thicknessof the resist film to be formed, and the like.

<Acid Generator Component; Component (B0)>

The resist composition of the present embodiment contains an acidgenerator component (B0) (hereafter, referred to as “component (B0)”)which generates acid upon exposure. The acid generator component (B0)preferably contains a compound (B0-1) represented by general formula(b0) shown below.

In formula (b0), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group which may have asubstituent, an alkyl group which may have a substituent or an alkenylgroup which may have a substituent, provided that Rb² and Rb³ may bemutually bonded to form a ring with the sulfur atom; and X1⁻ representsa monovalent counteranion capable of generating a strong acid.

In general formula (b0), Rb¹, Rb² and Rb³ are the same as defined forRb¹, Rb² and Rb³ in the aforementioned general formula (m0).

>In general formula (b0), X1⁻ represents a monovalent counteranioncapable of generating a strong acid.

X1⁻ is not particularly limited as long as it is a monovalentcounteranion capable of generating a strong acid. For example, the aciddissociation constant (pKa) is preferably 0 or less, more preferably −1or less. The lower limit of pKa is not particularly limited. Forexample, a monovalent counteranion capable of generating an acid havinga pKa of −15 can be used.

Further, in the present embodiment, as X1⁻, the anion moiety of acompound represented by any one of formulae (b-1) to (b-3) describedlater can be mentioned. Among these examples, the anion moiety of thecompound (B11) described later is preferable.

As the component (B0), one kind of these acid generator components maybe used alone, or two or more kinds of these acid generator componentsmay be used in combination.

When the resist composition of the present invention contains thecomponent (B0), the amount of the component (B0) relative to 100 partsby weight of the component (A) is preferably within a range from 0.5 to60 parts by weight, more preferably from 1 to 50 parts by weight, andstill more preferably from 1 to 40 parts by weight. When the amount ofthe component (B0) is within the above-mentioned range, the effects ofthe present invention can be enhanced. In addition, it is presumed thatthe solubility in a solvent and sensitivity are also improved.

<Acid Diffusion Control Agent; Component (D)>

The resist composition of the present embodiment may include, inaddition to the components (A) and (B), an acid diffusion control agent(hereafter, sometimes referred to as “component (D)”).

The component (D) functions as an acid diffusion control agent, i.e., aquencher which traps the acid generated from the component (B) and thelike upon exposure.

In the present invention, the component (D) may be a photodecomposablebase (D1) (hereafter, referred to as “component (D1)”) which isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion, or a nitrogen-containing organic compound (D2)(hereafter, referred to as “component (D2)”) which does not fall underthe definition of component (D1).

[Component (D1)]

When a resist pattern is formed using a resist composition containingthe component (D1), the contrast between exposed portions and unexposedportions is improved.

The component (D1) is not particularly limited, as long as it isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion. As the component (D1), at least one compound selectedfrom the group consisting of a compound represented by general formula(d1-1) shown below (hereafter, referred to as “component (d1-1)”), acompound represented by general formula (d1-2) shown below (hereafter,referred to as “component (d1-2)”) and a compound represented by generalformula (d1-3) shown below (hereafter, referred to as “component(d1-3)”) is preferably used.

At exposed portions, the components (d1-1) to (d1-3) are decomposed andthen lose the ability of controlling of acid diffusion (i.e., basicity),and therefore the components (d1-1) to (d1-3) cannot function as aquencher, whereas at unexposed portions, the components (d1-1) to (d1-3)functions as a quencher.

In the formulae, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, provided that,the carbon atom adjacent to the sulfur atom within the Rd² in theformula (d1-2) has no fluorine atom bonded thereto; Yd¹ represents asingle bond or a divalent linking group; and M^(m+) each independentlyrepresents a cation having a valency of m.

{Component (d1-1)}—Anion Moiety

In formula (d1-1), Rd¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹.

Among these, as the group for Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like alkyl group which may have a substituentare preferable. Examples of the substituent for these groups include ahydroxy group, an oxo group, an alkyl group, an aryl group, a fluorineatom, a fluorinated alkyl group, a lactone-containing cyclic grouprepresented by any one of the aforementioned formulae (a2-r-1) to(a2-r-7), an ether bond, an ester bond, and a combination thereof. Inthe case where an ether bond or an ester bond is included as thesubstituent, the substituent may be bonded via an alkylene group, and alinking group represented by any one of formulae (y-al-1) to (y-al-5)shown below is preferable.

The aromatic hydrocarbon group is preferably an aryl group such as aphenyl group or a naphthyl group.

Examples of the aliphatic cyclic group include groups in which one ormore hydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane.

As the chain-like hydrocarbon group, a chain-like alkyl group ispreferable. The chain-like alkyl group preferably has 1 to 10 carbonatoms, and specific examples thereof include a linear alkyl group suchas a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl ora decyl group, and a branched alkyl group such as a 1-methylethyl group,a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group or a 4-methylpentyl group.

In the case where the chain-like alkyl group is a fluorinated alkylgroup having a fluorine atom or a fluorinated alkyl group, thefluorinated alkyl group preferably has 1 to 11 carbon atoms, morepreferably 1 to 8 carbon atoms, and still more preferably 1 to 4 carbonatoms. The fluorinated alkyl group may contain an atom other thanfluorine. Examples of the atom other than fluorine include an oxygenatom, a carbon atom, a hydrogen atom, a sulfur atom and a nitrogen atom.

As Rd¹, a fluorinated alkyl group in which part or all of the hydrogenatoms constituting a linear alkyl group have been substituted withfluorine atom(s) is preferable, and a fluorinated alkyl group in whichall of the hydrogen atoms constituting a linear alkyl group have beensubstituted with fluorine atoms (i.e., a linear perfluoroalkyl group) ismore preferable.

Specific examples of preferable anion moieties for the component (d1-1)are shown below.

Cation Moiety

In formula (d1-1), M^(m+) represents an organic cation having a valencyof m (excluding the cation moiety of the compound (D0), as defined forM′^(m+) described later).

The organic cation for M^(m+) is not particularly limited, and examplesthereof include the same cation moieties as those represented byformulae (ca-1) to (ca-4) shown below, and cation moieties representedby formulae (ca-1-1) to (ca-1-63) shown below are preferable.

As the component (d1-1), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-2)}—Anion Moiety

In formula (d1-2), Rd² represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹,

provided that, the carbon atom adjacent to the sulfur atom within Rd²group has no fluorine atom bonded thereto (i.e., the carbon atomadjacent to the sulfur atom within Rd² group does not substituted with afluorine atom). As a result, the anion of the component (d1-2) becomesan appropriately weak acid anion, thereby improving the quenchingability of the component (D).

As Rd², an aliphatic cyclic group which may have a substituent ispreferable, and a group in which one or more hydrogen atoms have beenremoved from adamantane, norbornane, isobornane, tricyclodecane,tetracyclododecane or camphor (which may have a substituent) is morepreferable.

The hydrocarbon group for Rd² may have a substituent. As thesubstituent, the same groups as those described above for substitutingthe hydrocarbon group (e.g., aromatic hydrocarbon group, aliphatichydrocarbon group) for Rd¹ in the formula (d1-1) can be mentioned.

Specific examples of preferable anion moieties for the component (d1-2)are shown below.

Cation Moiety

In formula (d1-2), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-2), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-3)}—Anion Moiety

In formula (d1-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹, and a cyclic group containing afluorine atom, a chain-like alkyl group or a chain-like alkenyl group ispreferable. Among these, a fluorinated alkyl group is preferable, andmore preferably the same fluorinated alkyl groups as those describedabove for Rd¹.

In formula (d1-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹.

Among these, an alkyl group which may have substituent, an alkoxy groupwhich may have substituent, an alkenyl group which may have substituentor a cyclic group which may have substituent is preferable.

The alkyl group for Rd⁴ is preferably a linear or branched alkyl groupof 1 to 5 carbon atoms, and specific examples include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl group,and a neopentyl group. Part of the hydrogen atoms within the alkyl groupfor Rd⁴ may be substituted with a hydroxy group, a cyano group or thelike.

The alkoxy group for Rd⁴ is preferably an alkoxy group of 1 to 5 carbonatoms, and specific examples thereof include a methoxy group, an ethoxygroup, an n-propoxy group, an iso-propoxy group, an n-butoxy group and atert-butoxy group. Among these, a methoxy group and an ethoxy group arepreferable.

As the alkenyl group for Rd⁴, the same groups as those described abovefor R¹⁰¹ can be mentioned, and a vinyl group, a propenyl group (an allylgroup), a 1-methylpropenyl group and a 2-methylpropenyl group arepreferable. These groups may have an alkyl group of 1 to 5 carbon atomsor a halogenated alkyl group of 1 to 5 carbon atoms as a substituent.

As the cyclic group for Rd⁴, the same groups as those described abovefor R¹⁰¹ can be mentioned. Among these, as the cyclic group, analicyclic group (e.g., a group in which one or more hydrogen atoms havebeen removed from a cycloalkane such as cyclopentane, cyclohexane,adamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane) or an aromatic group (e.g., a phenyl group or anaphthyl group) is preferable. When Rd⁴ is an alicyclic group, theresist composition can be satisfactorily dissolved in an organicsolvent, thereby improving the lithography properties. Alternatively,when Rd⁴ is an aromatic group, the resist composition exhibits anexcellent photoadsorption efficiency in a lithography process using EUVor the like as the exposure source, thereby resulting in the improvementof the sensitivity and the lithography properties.

In formula (d1-3), Yd¹ represents a single bond or a divalent linkinggroup.

The divalent linking group for Yd¹ is not particularly limited, andexamples thereof include a divalent hydrocarbon group (aliphatichydrocarbon group, or aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Assuch groups, the same divalent linking groups as those described abovefor Ya²¹ in the formula (a2-1) can be mentioned.

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup or a combination of these is preferable. As the alkylene group, alinear or branched alkylene group is more preferable, and a methylenegroup or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d1-3)are shown below.

Cation Moiety

In formula (d1-3), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-3), one type of compound may be used, or two ormore types of compounds may be used in combination.

As the component (D1), one type of the aforementioned components (d1-1)to (d1-3), or at least two types of the aforementioned components (d1-1)to (d1-3) can be used in combination.

The amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 10 parts byweight, more preferably from 0.5 to 8 parts by weight, and still morepreferably from 1 to 8 parts by weight.

When the amount of the component (D1) is at least as large as the lowerlimit of the above-mentioned range, excellent lithography properties andexcellent resist pattern shape can be obtained. On the other hand, whenthe amount of the component (D1) is no more than the upper limit of theabove-mentioned range, sensitivity can be maintained at a satisfactorylevel, and through-put becomes excellent.

The production methods of the components (d1-1) to (d1-3) are notparticularly limited, and the components (d1-1) to (d1-3) can beproduced by conventional methods.

The amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 15.0 parts byweight, more preferably from 0.5 to 10.0 parts by weight, and still morepreferably from 1.0 to 8.0 parts by weight. When the amount of at leastas large as the lower limit of the above-mentioned range, excellentlithography properties and excellent resist pattern shape can beobtained. On the other hand, when the amount of the component (D) is nomore than the upper limit of the above-mentioned range, sensitivity canbe maintained at a satisfactory level, and through-put becomesexcellent.

(Component (D2))

The component (D) may contain a nitrogen-containing organic compound(D2) (hereafter, referred to as component (D2)) which does not fallunder the definition of component (D1).

The component (D2) is not particularly limited, as long as it functionsas an acid diffusion control agent, and does not fall under thedefinition of the component (D1). As the component (D2), any of theconventionally known compounds may be selected for use. Among these, analiphatic amine, particularly a secondary aliphatic amine or tertiaryaliphatic amine is preferable.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group of no more than 12 carbon atoms (i.e., alkylaminesor alkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly desirable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine,and piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, andspecific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene,1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris {2-(2-methoxyethoxy)ethyl}amine,tris {2-(2-methoxyethoxymethoxy)ethyl}amine, tris{2-(1-methoxyethoxy)ethyl}amine, tris {2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanolaminetriacetate, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.

Examples of aromatic amines include aniline, pyridine,4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole andderivatives thereof, as well as diphenylamine, triphenylamine,tribenzylamine, 2,6-diisopropylaniline andN-tert-butoxycarbonylpyrrolidine.

As the component (D2), one type of compound may be used alone, or two ormore types may be used in combination.

The component (D2) is typically used in an amount within a range from0.01 to 5.0 parts by weight, relative to 100 parts by weight of thecomponent (A). When the amount of the component (D) is within theabove-mentioned range, the shape of the resist pattern and the postexposure stability of the latent image formed by the pattern-wiseexposure of the resist layer are improved.

As the component (D), one type of compound may be used, or two or moretypes of compounds may be used in combination.

When the resist composition of the present invention contains thecomponent (D), the amount of the component (D) relative to 100 parts byweight of the component (A) is preferably within a range from 0.1 to 15parts by weight, more preferably from 0.3 to 12 parts by weight, andstill more preferably from 0.5 to 12 parts by weight. When the amount ofthe component (D) is at least as large as the lower limit of theabove-mentioned range, various lithography properties (such as LWR) ofthe resist composition are improved. Further, a resist pattern having anexcellent shape can be obtained. On the other hand, when the amount ofthe component (D) is no more than the upper limit of the above-mentionedrange, sensitivity can be maintained at a satisfactory level, andthrough-put becomes excellent.

In the present embodiment, the component (D) preferably includes acompound (D0) represented by general formula (d0) shown below. Thecompound (D0) preferably includes a compound (D11) shown below. In thecase where the acid diffusion control agent (D) includes the compound(D0), the amount of the compound (D0) relative to 100 parts by weight ofthe component (A) is preferably 0.1 to 30 parts by weight, morepreferably 0.3 to 20 parts by weight, and still more preferably 0.5 to15 parts by weight. When the above-mentioned range is satisfied, theeffects of the present invention are enhanced. In the component (D), theamount of the compound (D0) based on the total weight of the component(D) is preferably 25% by weight or more, more preferably 50% by weightor more, still more preferably 75% by weight or more, and may be even100% by weight. When the amount is 25% by weight or more, the effects ofthe present invention are improved. In addition, it is presumed that thesolubility in a solvent and sensitivity are also improved.

In formula (d0), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group which may have asubstituent, an alkyl group which may have a substituent or an alkenylgroup which may have a substituent, provided that Rb² and Rb³ may bemutually bonded to form a ring with the sulfur atom; and X2⁻ representsa monovalent counteranion capable of generating a weak acid.

In general formula (d0), Rb¹, Rb² and Rb³ are the same as defined forRb¹, Rb² and Rb³ in the aforementioned general formula (m0).

In general formula (d0), X2⁻ represents a monovalent counteranioncapable of generating a weak acid.

X2⁻ is not particularly limited as long as it is a monovalentcounteranion capable of generating a weak acid. For example, the aciddissociation constant (pKa) is preferably more than 0, more preferably0.2 or more. The upper limit of pKa is not particularly limited. Forexample, a monovalent counteranion capable of generating an acid havinga pKa of 10 can be used.

In the present invention, the anion for X1⁻ is the same as defined forthe anion moiety within the aforementioned formulae (d1-1) to (d1-3).

(Third Resist Composition)

A third resist composition according to the present embodiment is aresist composition which generates acid upon exposure and exhibitschanged solubility in a developing solution under action of acid, andincludes a compound (D0) represented by the aforementioned generalformula (d0) as an acid diffusion control agent (D).

In the case where the resist composition of the present embodiment is aresist composition which generates acid upon exposure and exhibitschanged solubility in a developing solution under action of acid, thecomponent (A1) preferably includes a structural unit (a6) whichgenerates acid upon exposure. In the case where the component (A1) doesnot include the structural unit (a6), the resist composition preferablyincludes the component (B) described later.

(Structural Unit (a6))

The structural unit (a6) is not particularly limited as long as itgenerates acid upon exposure. For example, a structural unitcopolymerizable with the aforementioned structural unit (a1) and inwhich a structure proposed as an acid generator for a conventionalchemically amplified resist has been introduced can be used.

Preferable examples of the structural unit copolymerizable with thestructural unit (a1) include a structural unit derived from a(meth)acrylate ester and a structural unit derived from hydroxystyrene.

Preferable examples of a compound having a structure proposed as an acidgenerator for a conventional chemically amplified resist include thecomponent (B) described later.

Examples of the structural unit (a6) include a structural unit (a6c)having an anion group which generates an acid upon exposure on a sidechain thereof, and a structural unit (a6c) which has a cation group thatis decomposed upon exposure on a side chain thereof.

Structural Unit (a6a)

The structural unit (a6c) is a structural unit having an anion groupwhich generates an acid upon exposure on a side chain thereof.

The anion group which generates acid upon exposure is not particularlylimited, and a sulfonic acid ion, an amide ion or a methide anion ispreferable.

Among these, as the anion group, a group represented by any one ofgeneral formulae (a6a-r-1), (a6a-r-2) or (a6a-r-3) shown below ispreferable.

In the formulae, Va′⁶¹ represents a divalent hydrocarbon group having afluorine atom; La′⁶³ to La′⁶⁵ each independently represents —SO₂— or asingle bond; Ra′⁶¹ to Ra′⁶³ each independently represents a hydrocarbongroup.

In formula (a6a-r-1), Va′⁶¹ represents a divalent hydrocarbon grouphaving a fluorine atom.

The divalent hydrocarbon group for Va′⁶¹ may be either an aliphatichydrocarbon group or an aromatic hydrocarbon group.

An “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

The linear or branched aliphatic hydrocarbon group preferably has 1 to10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4,and most preferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

The linear or branched aliphatic hydrocarbon group has a fluorine atom,and all of the hydrogen atoms of the aliphatic hydrocarbon group may besubstituted with fluorine. Further, in addition to fluorine, thealiphatic hydrocarbon group may be substituted with an oxo group (═O).

As examples of the hydrocarbon group containing a ring in the structurethereof, a cyclic aliphatic hydrocarbon group containing a hetero atomin the ring structure thereof and may have a substituent (a group inwhich two hydrogen atoms have been removed from an aliphatic hydrocarbonring), a group in which the cyclic aliphatic hydrocarbon group is bondedto the terminal of the aforementioned chain-like aliphatic hydrocarbongroup, and a group in which the cyclic aliphatic group is interposedwithin the aforementioned linear or branched aliphatic hydrocarbongroup, can be given. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be either a polycyclic groupor a monocyclic group. As the monocyclic aliphatic hydrocarbon group, agroup in which 2 hydrogen atoms have been removed from a monocycloalkaneis preferable. The monocycloalkane preferably has 3 to 6 carbon atoms,and specific examples thereof include cyclopentane and cyclohexane. Asthe polycyclic group, a group in which two hydrogen atoms have beenremoved from a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The cyclic aliphatic hydrocarbon group has a fluorine atom, and all ofthe hydrogen atoms of the cyclic aliphatic hydrocarbon group may besubstituted with fluorine. Further, in addition to fluorine, the cyclicaliphatic hydrocarbon group may be substituted with an alkyl group, analkoxy group, a hydroxy group, an oxo group (═O) or the like. Thesesubstituents are the same as defined above.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

The aromatic hydrocarbon group for the divalent hydrocarbon grouprepresented by Va′⁶¹ is a hydrocarbon group having at least one aromaticring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2) π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20, still more preferably 6 to 15,and most preferably 6 to 12. Here, the number of carbon atoms within asubstituent(s) is not included in the number of carbon atoms of thearomatic hydrocarbon group. Examples of the aromatic ring includearomatic hydrocarbon rings, such as benzene, naphthalene, anthracene andphenanthrene; and aromatic hetero rings in which part of the carbonatoms constituting the aforementioned aromatic hydrocarbon rings hasbeen substituted with a hetero atom. Examples of the hetero atom withinthe aromatic hetero rings include an oxygen atom, a sulfur atom and anitrogen atom.

Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring or aromatic hetero ring (arylene group orheteroarylene group); a group in which two hydrogen atoms have beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (a group in which onehydrogen atom has been removed from the aryl group within theaforementioned arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group, or a heteroarylalkylgroup). The alkylene group which is bonded to the aforementioned arylgroup or heteroaryl group preferably has 1 to 4 carbon atoms, morepreferably 1 or 2 carbon atoms, and most preferably 1 carbon atom.

The aromatic hydrocarbon group has a fluorine atom, and all of thehydrogen atoms of the aromatic hydrocarbon group may be substituted withfluorine. Further, in addition to fluorine, the cyclic aliphatichydrocarbon group may be substituted with an alkyl group, an alkoxygroup, a hydroxy group, an oxo group (═O) or the like. The alkyl groupand the alkoxy group as the substituent are the same as defined for thealkyl group and the alkoxy group as the substituent for the cyclicaliphatic hydrocarbon group.

Among the anion groups represented by formula (a6a-r-1), a grouprepresented by general formula (a6a-r-11) shown below is preferable.

In the formula, R^(f1) and R^(f2) each independently represents ahydrogen atom, an alkyl group, a fluorine atom or a fluorinated alkylgroup, provided that at least one of R^(f1) and R^(f2) represents afluorine atom or a fluorinated alkyl group; and p0 represents an integerof 1 to 8.

In formula (a6a-r-11), each of R^(f1) and R^(f2) independentlyrepresents a hydrogen atom, an alkyl group, a fluorine atom or afluorinated alkyl group, provided that at least one of R^(f1) and R^(f2)represents a fluorine atom or a fluorinated alkyl group.

The alkyl group for R^(f1) and R^(f2) is preferably an alkyl group of 1to 5 carbon atoms, and specific examples thereof include a methyl group,an ethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl groupand a neopentyl group.

The fluorinated alkyl group for R^(f1) and R^(f2) is preferably a groupin which part or all of the hydrogen atoms within the aforementionedalkyl group for R^(f1) and R^(f2) have been substituted with a fluorineatom.

As R^(f1) and R^(f2), a fluorine atom or a fluorinated alkyl group ispreferable.

In formula (a6a-r-11), p0 represents an integer of 1 to 8, preferably aninteger of 1 to 4, and more preferably 1 or 2.

In formula (a6a-r-2), as the hydrocarbon group for Ra′⁶¹, an alkylgroup, a monovalent alicyclic hydrocarbon group, an aryl group and anaralkyl group can be mentioned.

The alkyl group for Ra′⁶¹ preferably has 1 to 8 carbon atoms, morepreferably 1 to 6 carbon atoms, and still more preferably 1 to 4 carbonatoms. The alkyl group may be linear or branched. Specific examples ofpreferable alkyl groups include a methyl group, an ethyl group, a propylgroup, a butyl group, a hexyl group and an octyl group.

The monovalent alicyclic hydrocarbon group for Ra′⁶¹ preferably has 3 to20 carbon atoms, and more preferably 3 to 12 carbon atoms. Themonovalent alicyclic hydrocarbon group may be polycyclic or monocyclic.As the monocyclic alicyclic hydrocarbon group, a group in which one ormore hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclobutane, cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 12 carbon atoms. Examples of the polycycloalkane include adamantane,norbornane, isobornane, tricyclodecane and tetracyclododecane.

The aryl group for Ra′⁶¹ preferably has 6 to 18 carbon atoms, and morepreferably 6 to 10 carbon atoms. Specifically, a phenyl group isparticularly desirable.

As a preferable examples of the aralkyl group for Ra′⁶¹, a group inwhich an alkylene group of 1 to 8 carbon atoms has been bonded to theaforementioned “aryl group for Ra′⁶¹” can be mentioned. An aralkyl groupin which an alkylene group of 1 to 6 carbon atoms has been bonded to theaforementioned “aryl group for Ra′⁶¹” is more preferable, and an aralkylgroup in which an alkylene group of 1 to 4 carbon atoms has been bondedto the aforementioned “aryl group for Ra′⁶¹” is most preferable.

The hydrocarbon group for Ra′⁶¹ preferably has part or all of thehydrogen atoms within the hydrocarbon group substituted with fluorine,and the hydrocarbon group more preferably has 30 to 100% of the hydrogenatoms substituted with fluorine. Among these, a perfluoroalkyl group inwhich all of the hydrogen atoms within the alkyl group have beensubstituted with fluorine atoms is particularly desirable.

In formula (a6a-r-3), La′⁶³ to La′⁶⁵ each independently represents —SO₂—or a single bond, and Ra′⁶² and Ra′⁶³ each independently represents ahydrocarbon group. The hydrocarbon group for Ra′⁶² and Ra′⁶³ is the sameas defined for the hydrocarbon group for Ra′⁶¹.

Preferable examples of the structural unit (a6a) include structuralunits represented by general formulae (a6a-1) to (a6a-8) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ra⁶¹is a group represented by the aforementioned formula (a6a-r-1); Ra⁶² isa group represented by the aforementioned formula (a6a-r-2) or(a6a-r-3); Ra⁶³ is a group represented by the aforementioned formula(a6a-r-3); Ra″⁶¹ to Ra″⁶⁴ each independently represents a hydrogen atom,a fluorine atom, an alkyl group of 1 to 5 carbon atoms or a fluorinatedalkyl group; n_(a61) and n_(a62) each independently represents aninteger of 1 to 10; n_(a63) represents an integer of 0 to 10;

Va″⁶¹ represents a divalent cyclic hydrocarbon group; La″⁶¹ represents—C(═O)—O—, —O—C(═O)—O— or —O—CH₂—C(═O)—O—; Va″⁶² represents a divalenthydrocarbon group; Ra″⁶⁵ represents a hydrogen atom or an alkyl group of1 to 5 carbon atoms; La″⁶² represents —C(═O)—O—, —O—C(═O)—O— or—NH—C(═O)—O—; Ya″⁶¹ represents a divalent linking group containing acyclic hydrocarbon group; Va″⁶³ represents a divalent cyclic hydrocarbongroup or a single bond; m represents an integer of 1 or more; and eachM^(m+) independently represents an organic cation having a valency of m.

In formulae (a6a-1) to (a6a-8), R is the same as defined for R in theaforementioned formula (a0-1).

In formulae (a6a-1) to (a6a-4), each Ra⁶¹ independently represents agroup represented by the aforementioned formula (a6a-r-1). In formulae(a6a-5) to (a6a-7), each Ra⁶² independently represents a grouprepresented by the aforementioned formula (a6a-r-2) or (a6a-r-3). Informula (a6a-8), Ra⁶³ represents a group represented by theaforementioned formula (a6a-r-3).

In formulae (a6a-2) and (a6a-5) to (a6a-7), Ra″⁶¹ to Ra″⁶⁴ eachindependently represents a hydrogen atom, a fluorine atom, an alkylgroup of 1 to 5 carbon atoms or a fluorinated alkyl group. Examples ofthe fluorinated alkyl group for Ra″⁶¹ to Ra″⁶⁴ include groups in whichpart or all of the hydrogen atoms within the alkyl group of 1 to 5carbon atoms have been substituted with a fluorine atom.

In formulae (a6a-2), (a6a-5) and (a6a-6), each n_(a61) independentlyrepresents an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 4, and still more preferably 1 or 2.

In formula (a6a-6), n_(a62) represents an integer of 1 to 10, preferablyan integer of 1 to 8, more preferably an integer of 1 to 4, and stillmore preferably 1 or 2.

In formula (a6a-7), n_(a63) represents an integer of 0 to 10, preferablyan integer of 0 to 5, more preferably an integer of 0 to 3, and stillmore preferably 0.

In formula (a6a-3), Va″⁶¹ represents a divalent cyclic hydrocarbongroup, and is the same as defined for the “aliphatic hydrocarbon groupcontaining a ring in the structure thereof” and “aromatic hydrocarbongroup” explained above in relation to Va′⁶¹ in the aforementionedformula (a6a-r-1).

La″⁶¹ represents —C(═O)—O—, —O—C(═O)—O— or —O—CH₂—C(═O)—O—.

In formula (a6a-4), Va″⁶² represents a divalent hydrocarbon group, andis the same as defined for the divalent hydrocarbon group explainedabove in relation to Va′⁶¹ in the aforementioned formula (a6a-r-1).

Ra″⁶⁵ represents a hydrogen atom or an alkyl group of 1 to 5 carbonatoms.

In formula (a6a-6), La″⁶² represents —C(═O)—O—, —O—C(═O)—O— or—NH—C(═O)—O—.

In formula (a6a-7), Ya″⁶¹ represents a divalent cyclic hydrocarbongroup, and is the same as defined for the “aliphatic hydrocarbon groupcontaining a ring in the structure thereof”, the “aromatic hydrocarbongroup” and the “divalent linking group containing a hetero atom” (havingan “aliphatic hydrocarbon group containing a ring in the structurethereof” or an “aromatic hydrocarbon group”) described later in relationto the divalent linking group for Ya²¹ in general formula (a2-1).

In formula (a6a-8), Va″⁶³ represents a divalent cyclic hydrocarbon groupor a single bond. The divalent cyclic hydrocarbon group for Va″⁶³ is thesame as defined for the “aliphatic hydrocarbon group containing a ringin the structure thereof” and “aromatic hydrocarbon group” explainedabove in relation to Va′⁶¹ in the aforementioned formula (a6a-r-1).

In formula (a6a-1) to (a6a-8), m represents an integer of 1 or more, andeach M^(m+) independently represents an organic cation having a valencyof m (provided that the cation of the compound (B0-1) is excluded).

The organic cation for M^(m+) is not particularly limited. As theorganic cation, an onium cation having a valency of m is preferable,more preferably a sulfonium cation or an iodonium cation, mostpreferably an organic cation represented by any one of formulae (ca-1)to (ca-4) described later.

Specific examples of structural unit represented by formula (a6a-1) areshown below. (M^(m+))_(1/m) is the same as defined above.

Specific examples of structural unit represented by formula (a6a-2) areshown below.

Specific examples of structural unit represented by formula (a6a-3) areshown below.

Specific examples of structural unit represented by formula (a6a-4) areshown below.

Specific examples of structural unit represented by formula (a6a-5) areshown below.

Specific examples of structural unit represented by formula (a6a-6) areshown below.

Specific examples of structural unit represented by formula (a6a-7) areshown below.

Specific examples of structural unit represented by formula (a6a-8) areshown below.

Structural Unit (a6c)

The structural unit (a6a) is a structural unit having a cation groupwhich is decomposed upon exposure on a side chain thereof.

The cation group decomposed upon exposure is not particularly limited,and a group represented by general formula (a6c-r-1) shown below ispreferable.

In the formula, Ra′^(61c) and Ra′^(62c) each independently represents anaryl group which may have a substituent, an alkyl group which may have asubstituent or an alkenyl group which may have a substituent; Va′^(61c)represents an arylene group, an alkylene group or an alkenylene group;provided that Ra′^(61c), Ra′^(62c) and Va′^(61c) may be mutually bondedto form a ring with the sulfur atom.

In formula (a6c-r-1), Ra′^(61c) and Ra′^(62c) each independentlyrepresents an aryl group which may have a substituent, an alkyl groupwhich may have a substituent or an alkenyl group which may have asubstituent. Ra′^(61c) and Ra′^(62c) are the same as defined for the“aryl group which may have a substituent”, the “alkyl group which mayhave a substituent” and the “alkenyl group which may have a substituent”for R²⁰¹ to R²⁰³ in the aforementioned formula (ca-1).

Va′^(61c) represents an arylene group, an alkylene group or analkenylene group, and examples thereof include a group in which onehydrogen atom has been removed from an aryl group, an alkyl group or analkenyl group for Ra′^(61c) and Ra′^(62c).

Ra′^(61c), Ra′^(62c) and Va′^(61c) may be mutually bonded to form a ringwith the sulfur atom. Examples of the formed ring structure include agroup in which one hydrogen atom has been removed from the ring formedby R²⁰¹ to R²⁰³ mutually bonded with the sulfur atom in theaforementioned formula (ca-1).

Preferable examples of the structural unit (a6c) include structuralunits represented by general formulae (a6c-1) to (a6c-3) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; eachVa^(61c) independently represents an alkylene group of 1 to 5 carbonatoms; Va^(62c) and Va^(64c) each independently represents an alkylenegroup of 1 to 10 carbon atoms; Va^(63c) represents an aliphatic cyclicgroup or a single bond; na^(61c) represents an integer of 0 to 2;na^(62c) represents 0 or 1; Ra^(6c) is a group represented by theaforementioned formula (a6c-r-1); and A represents a counteranion.

In formulae (a6c-1) to (a6c-3), R is the same as defined for R in theaforementioned formula (a0-1). Each Ra^(61c) independently represents agroup represented by the aforementioned formula (a6c-r-1).

In formulae (a6c-2) and (a6c-3), each Va^(61c) independently representsan alkylene group of 1 to 5 carbon atoms, preferably an alkylene groupof 1 to 3 carbon atoms, and more preferably a methylene group.

In formula (a6c-3), Va^(62c) and Va^(64c) independently represents analkylene group of 1 to 10 carbon atoms, preferably an alkylene group of1 to 8 carbon atoms, more preferably an alkylene group of 1 to 5 carbonatoms, and still more preferably an alkylene group of 1 to 3 carbonatoms.

In formula (a6c-3), Va^(63c) represents an aliphatic cyclic group or asingle bond. The aliphatic cyclic group for Va^(63c) is the same asdefined for the aliphatic cyclic group explained above in relation toVa′⁶¹ in the aforementioned formula (a6a-r-1).

na^(61c) represents an integer of 0 to 2, preferably 1 or 2.

na^(62c) represents 0 or 1.

In formulae (a6c-1) to (a6c-3), A⁻ represents a counteranion.

The counteranion for A⁻ is not particularly limited, and examplesthereof include the anion moiety of an onium salt acid generatorrepresented by general formula (b-1), (b-2) or (b-3) described later inrelation to the component (B). The counteranion is preferably the anionmoiety of an onium salt acid generator represented by general formula(b-1), more preferably a fluorinated alkylsulfonate ion of 1 to 8 carbonatoms (preferably 1 to 4 carbon atoms) or at least one member selectedfrom anions represented by general formulae (an-1) to (an-3) describedlater.

Specific examples of the structural unit represented by formula (a6c-1),(a6c-2) or (a6c-3) are shown below. A⁻ is the same as defined above,

As the structural unit (a6) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

As the structural unit (a6a), a structural unit represented by generalformula (a6a-1) or (a6a-2) is preferable. As the structural unit (a6c),a structural unit represented by general formula (a6c-1) shown below ispreferable.

Among these, as the structural unit (a6), the structural unit (a6a) ispreferable.

The amount of the structural unit (a6) within the component (A1) basedon the combined total of all structural units constituting the component(A1) is preferably 0.5 to 30 mol %, more preferably 1 to 20 mol %, andstill more preferably 1.5 to 15 mol %.

When the amount of the structural unit (a6) is at least as large as thelower limit of the above-mentioned range, roughness can be reduced, andan excellent resist pattern can be reliably obtained. On the other hand,when the amount of the structural unit (a6) is no more than the upperlimit of the above-mentioned range, a good balance can be achieved withthe other structural units, and the lithography properties can beimproved.

The third resist composition according to the present embodiment maycontain an acid generator component (B) described below.

As the component (B), there is no particular limitation, and any of theknown acid generators used in conventional chemically amplified resistcompositions can be used.

Examples of these acid generators are numerous, and include onium saltacid generators such as iodonium salts and sulfonium salts; oximesulfonate acid generators; diazomethane acid generators such as bisalkylor bisaryl sulfonyl diazomethanes and poly(bis-sulfonyl)diazomethanes;nitrobenzylsulfonate acid generators; iminosulfonate acid generators;and disulfone acid generators. Among these, it is preferable to use anonium salt acid generator.

As the onium salt acid generator, a compound represented by generalformula (b-1) below (hereafter, sometimes referred to as “component(b-1)”), a compound represented by general formula (b-2) below(hereafter, sometimes referred to as “component (b-2)”) or a compoundrepresented by general formula (b-3) below (hereafter, sometimesreferred to as “component (b-3)”) may be used.

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring; R¹⁰⁶ and R¹⁰⁷ may be mutually bonded to form a ring;R¹⁰² represents a fluorine atom or a fluorinated alkyl group of 1 to 5carbon atoms; Y¹⁰¹ represents a single bond or a divalent linking groupcontaining an oxygen atom; V¹⁰¹ to V¹⁰³ each independently represents asingle bond, an alkylene group or a fluorinated alkylene group; L¹⁰¹ andL¹⁰² each independently represents a single bond or an oxygen atom; L¹⁰³to L¹⁰⁵ each independently represents a single bond, —CO— or —SO₂—; andM′^(m+) represents an organic cation having a valency of m.

{Anion Moiety}Anion Moiety of Component (b-1)

In the formula (b-1), R¹⁰¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent.

(Cyclic Group which May have a Substituent)

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group.

As the aromatic hydrocarbon group for R¹⁰¹, groups in which one hydrogenatom has been removed from an aromatic hydrocarbon ring described abovein relation to the divalent aromatic hydrocarbon group for Va¹ in theformula (a1-1) or an aromatic compound containing two or more aromaticring can be mentioned, and a phenyl group or a naphthyl group ispreferable.

As the cyclic aliphatic hydrocarbon group for R¹⁰¹, groups in which onehydrogen atom has been removed from a monocycloalkane or apolycycloalkane exemplified above in the explanation of the divalentaliphatic hydrocarbon group for Va¹ in the formula (a1-1) can bementioned. Among polycycloalkanes, a polycycloalkane having a bridgedring polycyclic skeleton, such as an adamantyl group or a norbornylgroup, and a polycycloalkane having a condensed ring polycyclicskeleton, such as a cyclic group having a steroid skeleton arepreferable. In the present specification, a steroid skeleton refers to askeleton (st) shown below which has three 6-membered rings and one5-membered ring bonded.

Further, the cyclic hydrocarbon group for R¹⁰¹ may contain a hetero atomlike as a heterocycle, and specific examples thereof includelactone-containing cyclic groups represented by the aforementionedgeneral formulas (a2-r-1) to (a2-r-7), —SO₂— containing cyclic groupsrepresented by the aforementioned formulas (a5-r-1) to (a5-r-4) andheterocycles shown below.

As the substituent for the cyclic hydrocarbon group for R¹⁰¹, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group or the like can be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

(Chain-Like Alkyl Group which May have a Substituent)

The chain-like alkyl group for R¹⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15, and most preferably 1 to 10. Specific examplesinclude a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, a decyl group, an undecyl group, a dodecyl group, a tridecylgroup, an isotridecyl group, a tetradecyl group, a pentadecyl group, ahexadecyl group, an isohexadecyl group, a heptadecyl group, an octadecylgroup, a nonadecyl group, an icosyl group, a henicosyl group and adocosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesinclude a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropylgroup, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutylgroup, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentylgroup, a 2-methylpentyl group, a 3-methylpentyl group and a4-methylpentyl group.

(Chain-Like Alkenyl Group which May have a Substituent)

The chain-like alkenyl group for R¹⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and most preferably 3carbon atoms. Examples of linear alkenyl groups include a vinyl group, apropenyl group (an allyl group) and a butynyl group. Examples ofbranched alkenyl groups include a 1-methylpropenyl group and a2-methylpropenyl group.

Among the above-mentioned examples, as the chain-like alkenyl group, apropenyl group is particularly desirable.

As the substituent for the chain-like alkyl group or alkenyl group forR¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group, an amino group, acyclic group for R¹⁰¹ or the like can be used.

Among these examples, as R¹⁰¹, a cyclic group which may have asubstituent is preferable, and a cyclic hydrocarbon group which may havea substituent is more preferable. Specifically, a phenyl group, anaphthyl group, a group in which one or more hydrogen atoms have beenremoved from a polycycloalkane, a lactone-containing cyclic grouprepresented by any one of the aforementioned formula (a2-r-1) to(a2-r-7), and an —SO₂— containing cyclic group represented by any one ofthe aforementioned formula (a5-r-1) to (a5-r-4).

In formula (b-1), Y¹⁰¹ represents a single bond or a divalent linkinggroup containing an oxygen atom.

In the case where Y¹⁰¹ is a divalent linking group containing an oxygenatom, Y¹⁰¹ may contain an atom other than an oxygen atom. Examples ofatoms other than an oxygen atom include a carbon atom, a hydrogen atom,a sulfur atom and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom includenon-hydrocarbon, oxygen atom-containing linking groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonylgroup (—O—C(═O)—), an amido bond (—C(═O)—NH—), a carbonyl group(—C(═O)—) and a carbonate bond (—O—C(═O)—O—); and combinations of theaforementioned non-hydrocarbon, hetero atom-containing linking groupswith an alkylene group. Furthermore, the combinations may have asulfonyl group (—SO₂—) bonded thereto. As the combination, the linkinggroup represented by formulas (y-al-1) to (y-al-7) shown below can bementioned.

In the formulae, V′¹⁰¹ represents a single bond or an alkylene group of1 to 5 carbon atoms; V′¹⁰² represents a divalent saturated hydrocarbongroup of 1 to 30 carbon atoms.

The divalent saturated hydrocarbon group for V′¹⁰² is preferably analkylene group of 1 to 30 carbon atoms.

The alkylene group for V′¹⁰¹ and V′¹⁰² may be a linear alkylene group ora branched alkylene group, and a linear alkylene group is preferable.

Specific examples of the alkylene group for V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂—]; an alkylmethylene group, such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; an alkylethylene group, suchas —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group) [—CH₂CH₂CH₂—]; analkyltrimethylene group, such as —CH(CH₃)CH₂CH₂— and —CH₂CH(CH₃)CH₂—; atetramethylene group [—CH₂CH₂CH₂CH₂—]; an alkyltetramethylene group,such as —CH(CH₃)CH₂CH₂CH₂—, —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylenegroup [—CH₂CH₂CH₂CH₂CH₂—].

Further, part of methylene group within the alkylene group for V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group of 5 to10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclicaliphatic hydrocarbon group for Ra′³ in the aforementioned formula(a1-r-1), and a cyclohexylene group, 1,5-adamantylene group or2,6-adamantylene group is preferable.

Y¹⁰¹ is preferably a divalent linking group containing an ether bond oran ester bond, and groups represented by the aforementioned formulas(y-al-1) to (y-al-5) are preferable.

In formula (b-1), V¹⁰¹ represents a single bond, an alkylene group or afluorinated alkylene group. The alkylene group and the fluorinatedalkylene group for V¹⁰¹ preferably has 1 to 4 carbon atoms. Examples ofthe fluorinated alkylene group for V¹⁰¹ include a group in which part orall of the hydrogen atoms within the alkylene group for V¹⁰¹ have beensubstituted with fluorine. Among these examples, as V¹⁰¹, a single bondor a fluorinated alkylene group of 1 to 4 carbon atoms is preferable.

In formula (b-1), R¹⁰² represents a fluorine atom or a fluorinated alkylgroup of 1 to 5 carbon atoms. R¹⁰² is preferably a fluorine atom or aperfluoroalkyl group of 1 to 5 carbon atoms, and more preferably afluorine atom.

As specific examples of anion moieties of the formula (b-1),

in the case where Y¹⁰¹ a single bond, a fluorinated alkylsulfonate anionsuch as a trifluoromethanesulfonate anion or a perfluorobutanesulfonateanion can be mentioned; and in the case where Y¹⁰¹ represents a divalentlinking group containing an oxygen atom, anions represented by formulae(an-1) to (an-3) shown below can be mentioned.

In the formulae, R″¹⁰¹ represents an aliphatic cyclic group which mayhave a substituent, a group represented by any one of the aforementionedformulae (r-hr-1) to (r-hr-6) or a chain-like alkyl group which may havea substituent; R″¹⁰² represents an aliphatic cyclic group which may havea substituent, a lactone-containing cyclic group represented by any oneof the aforementioned formulae (a2-r-1) to (a2-r-7) or an —SO₂—containing cyclic group represented by any one of the aforementionedformulae (a5-r-1) to (a5-r-4); R″¹⁰³ represents an aromatic cyclic groupwhich may have a substituent, an aliphatic cyclic group which may have asubstituent or a chain-like alkenyl group which may have a substituent;V″¹⁰¹ represents a fluorinated alkylene group; L″¹⁰¹ represents —C(═O)—or —SO₂—; v″ represents an integer of 0 to 3; q″ represents an integerof 1 to 20; and n″ represents 0 or 1.

As the aliphatic cyclic group for R″¹⁰¹, R″¹⁰² and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupfor R¹⁰¹ described above are preferable. As the substituent, the samegroups as those described above for substituting the cyclic aliphatichydrocarbon group for R¹⁰¹ can be mentioned.

As the aromatic cyclic group for R″¹⁰³ which may have a substituent, thesame groups as the aromatic hydrocarbon group for the cyclic hydrocarbongroup represented by R¹⁰¹ described above are preferable. Thesubstituent is the same as defined for the substituent for the aromatichydrocarbon group represented by R¹⁰¹.

As the chain-like alkyl group for R″¹ which may have a substituent, thesame groups as those described above for R¹⁰¹ are preferable. As thechain-like alkenyl group for R″¹⁰³ which may have a substituent, thesame groups as those described above for R¹⁰¹ are preferable. V″¹⁰¹ ispreferably a fluorinated alkylene group of 1 to 3 carbon atoms, and mostpreferably —CF₂—, —CF₂CF₂—, —CHFCF₂—, —CF(CF₃)CF₂— or —CH(CF₃)CF₂—.

Anion Moiety of Component (b-2)

In formula (b-2), R¹⁰⁴ and R¹⁰⁵ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and is the same as defined for R¹⁰¹ in formula (b-1). R¹⁰⁴and R¹⁰⁵ may be mutually bonded to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituentis preferable, and a linear or branched alkyl group or a linear orbranched fluorinated alkyl group is more preferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, morepreferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbonatoms. The smaller the number of carbon atoms of the chain-like alkylgroup for R¹⁰⁴ and R¹⁰⁵, the more the solubility in a resist solvent isimproved. Further, in the chain-like alkyl group for R¹⁰⁴ and R¹⁰⁵, itis preferable that the number of hydrogen atoms substituted withfluorine atoms is as large as possible because the acid strengthincreases and the transparency to high energy radiation of 200 nm orless or electron beam is improved. The fluorination ratio of thechain-like alkyl group is preferably from 70 to 100%, more preferablyfrom 90 to 100%, and it is particularly desirable that the chain-likealkyl group be a perfluoroalkyl group in which all hydrogen atoms aresubstituted with fluorine atoms.

In formula (b-2), V¹⁰² and V¹⁰³ each independently represents a singlebond, an alkylene group or a fluorinated alkylene group, and is the sameas defined for V¹⁰¹ in formula (b-1).

In formula (b-2), L¹⁰¹ and L¹⁰² each independently represents a singlebond or an oxygen atom.

Anion Moiety of Component (b-3)

In formula (b-3), R¹¹⁶ to R¹⁰⁸ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and is the same as defined for R¹⁰¹ in formula (b-1).

L¹⁰³ to L¹⁰⁵ each independently represents a single bond, —CO— or —SO₂—.

{Cation Moiety}

In formulae (b-1), (b-2) and (b-3), M′^(m+) represents an organic cationhaving a valency of m other than the cation moiety of the compound(B11), preferably a sulfonium cation or an iodonium cation, and mostpreferably a cation represented by any one of formulae (ca-1) to (ca-4)shown below.

In the formulae, R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² independently represents anaryl group, an alkyl group or an alkenyl group, provided that two ofR²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, or R²¹¹ and R²¹² may be mutually bonded toform a ring with the sulfur atom; R²⁰⁸ and R²⁰⁹ each independentlyrepresents a hydrogen atom or an alkyl group of 1 to 5 carbon atoms;R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent or an —SO₂— containing cyclic group which may have asubstituent; L²⁰¹ represents —C(═O)— or —C(═O)—O—; Y²⁰¹ eachindependently represents an arylene group, an alkylene group or analkenylene group; x represents 1 or 2; and W²⁰¹ represents a linkinggroup having a valency of (x+1).

As the aryl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹², an unsubstituted arylgroup of 6 to 20 carbon atoms can be mentioned, and a phenyl group or anaphthyl group is preferable.

The alkyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² is preferably achain-like or cyclic alkyl group having 1 to 30 carbon atoms.

The alkenyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² preferably has 2 to 10carbon atoms.

Specific examples of the substituent which R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹²may have include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl group,an arylthio group and groups represented by formulae (ca-r-1) to(ca-r-7) shown below.

The aryl group within the arylthio group as the substituent is the sameas defined for R¹⁰¹, and specific examples include a phenylthio groupand a biphenylthio group.

In the formulae, R′²⁰¹ each independently represents a hydrogen atom, acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent.

As the cyclic group which may have a substituent, the chain-like alkylgroup which may have a substituent and the chain-like alkenyl groupwhich may have a substituent for R′²⁰¹, the same groups as thosedescribed above for R¹⁰¹ can be mentioned. As the cyclic group which mayhave a substituent and chain-like alkyl group which may have asubstituent, the same groups as those described above for the aciddissociable group represented by the aforementioned formula (a1-r-2) canbe also mentioned.

When R²⁰¹ to R²⁰³, R²⁰⁶, R²⁰⁷, R²¹¹ and R²¹² are mutually bonded to forma ring with the sulfur atom, these groups may be mutually bonded via ahetero atom such as a sulfur atom, an oxygen atom or a nitrogen atom, ora functional group such as a carbonyl group, —SO—, —SO₂—, —SO₃—, —COO—,—CONH— or —N(R_(N))— (wherein R_(N) represents an alkyl group of 1 to 5carbon atoms). The ring containing the sulfur atom in the skeletonthereof is preferably a 3 to 10-membered ring, and most preferably a 5to 7-membered ring. Specific examples of the ring formed include athiophene ring, a thiazole ring, a benzothiophene ring, a thianthrenering, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthenering, a thioxanthone ring, a phenoxathiin ring, a tetrahydrothiopheniumring, and a tetrahydrothiopyranium ring.

R²⁰⁸ and R²⁰⁹ each independently represents a hydrogen atom or an alkylgroup of 1 to 5 carbon atoms, preferably a hydrogen atom or an alkylgroup of 1 to 3 carbon atoms, and when R²⁰⁸ and R²⁰⁹ each represents analkyl group, R²⁰⁸ and R²⁰⁹ may be mutually bonded to form a ring.

R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent, or an —SO₂— containing cyclic group which may have asubstituent.

Examples of the aryl group for R²¹⁰ include an unsubstituted aryl groupof 6 to 20 carbon atoms, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group for R²¹⁰, a chain-like or cyclic alkyl group having 1to 30 carbon atoms is preferable.

The alkenyl group for R²¹⁰ preferably has 2 to 10 carbon atoms.

As the —SO₂— containing cyclic group for R²¹⁰ which may have asubstituent, the same “—SO₂— containing cyclic groups” as thosedescribed above for Ra²¹ in the aforementioned general formula (a2-1)can be mentioned, and the group represented by the aforementionedgeneral formula (a5-r-1) is preferable.

Each Y²⁰¹ independently represents an arylene group, an alkylene groupor an alkenylene group.

Examples of the arylene group for Y²⁰¹ include groups in which onehydrogen atom has been removed from an aryl group given as an example ofthe aromatic hydrocarbon group for R¹⁰¹ in the aforementioned formula(b-1).

The alkylene group and the alkenylene group for Y²⁰¹ is the same asdefined for the aliphatic hydrocarbon group as the divalent linkinggroup represented by Va¹ in the aforementioned general formula (a1-1).

In the formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a linking group having a valency of (x+1), i.e., adivalent or trivalent linking group.

As the divalent linking group for W²⁰¹, a divalent hydrocarbon groupwhich may have a substituent is preferable, and as examples thereof, thesame hydrocarbon groups as those described above for Ya²¹ in the generalformula (a2-1) can be mentioned. The divalent linking group for W²⁰¹ maybe linear, branched or cyclic, and cyclic is more preferable. Amongthese, an arylene group having two carbonyl groups, each bonded to theterminal thereof is preferable. Examples of the arylene group include aphenylene group and a naphthylene group, and a phenylene group isparticularly desirable.

As the trivalent linking group for W²⁰¹, a group in which one hydrogenatom has been removed from the aforementioned divalent linking group forW²⁰¹ and a group in which the divalent linking group has been bonded toanother divalent linking group can be mentioned. The trivalent linkinggroup for W²⁰¹ is preferably a group in which 2 carbonyl groups arebonded to an arylene group.

Specific examples of preferable cations represented by formula (ca-1)include cations represented by formulae (ca-1-1) to (ca-1-63) shownbelow.

In the formulae, g1, g2 and g3 represent recurring numbers, wherein g1is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is aninteger of 0 to 20.

In the formulae, R″²⁰¹ represents a hydrogen atom or a substituent, andas the substituent, the same groups as those described above forsubstituting R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² can be mentioned.

Specific examples of preferable cations represented by formula (ca-3)include cations represented by formulae (ca-3-1) to (ca-3-6) shownbelow.

Specific examples of preferable cations represented by formula (ca-4)include cations represented by formulae (ca-4-1) and (ca-4-2) shownbelow.

As the component (B), one type of these acid generators may be usedalone, or two or more types may be used in combination.

When the resist composition of the present invention contains thecomponent (B), the amount of the component (B) relative to 100 parts byweight of the component (A) is preferably within a range from 0.5 to 60parts by weight, more preferably from 1 to 50 parts by weight, and stillmore preferably from 1 to 40 parts by weight. When the amount of thecomponent (B) is within the above-mentioned range, formation of a resistpattern can be satisfactorily performed. Further, by virtue of theabove-mentioned range, when each of the components are dissolved in anorganic solvent, a uniform solution can be obtained and the storagestability becomes satisfactory.

In the third resist composition according to the present embodiment, theacid generator component (B) may include the compound (B0-1) representedby the aforementioned formula (b0), and the compound (B0-1) preferablyincludes the compound (B11) described later. In the case where the acidgenerator component (B) includes the compound (B0-1), the amount of thecompound (B0-1) relative to 100 parts by weight of the component (A) ispreferably 0.5 to 60 parts by weight, more preferably 1 to 50 parts byweight, and still more preferably 1 to 40 parts by weight. When theabove-mentioned range is satisfied, the effects of the present inventionare enhanced. In the component (B), the amount of the compound (B0-1)based on the total weight of the component (B) is preferably 25% byweight or more, more preferably 50% by weight or more, still morepreferably 75% by weight or more, and may be even 100% by weight. Whenthe amount is 25% by weight or more, the effects of the presentinvention are improved. In addition, it is presumed that the solubilityin a solvent and sensitivity are also improved.

<Optional Components>

[Component (E)]

Furthermore, in the resist composition of the present invention, forpreventing any deterioration in sensitivity, and improving the resistpattern shape and the post exposure stability of the latent image formedby the pattern-wise exposure of the resist layer, at least one compound(E) (hereafter referred to as the component (E)) selected from the groupconsisting of an organic carboxylic acid, or a phosphorus oxo acid orderivative thereof can be added.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid and phosphinic acid. Among these, phosphonic acid is particularlydesirable.

Examples of oxo acid derivatives include esters in which a hydrogen atomwithin the above-mentioned oxo acids is substituted with a hydrocarbongroup. Examples of the hydrocarbon group include an alkyl group of 1 to5 carbon atoms and an aryl group of 6 to 15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonicacid, diphenyl phosphonate and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phosphinic acid estersand phenylphosphinic acid.

As the component (E), one type may be used alone, or two or more typesmay be used in combination.

The component (E) is typically used in an amount within a range from0.01 to 5.0 parts by weight, relative to 100 parts by weight of thecomponent (A).

[Component (F)]

The resist composition of the present invention may contain a fluorineadditive (hereafter, referred to as “component (F)”) for imparting waterrepellency to the resist film.

As the component (F), for example, a fluorine-containing polymericcompound described in Japanese Unexamined Patent Application, FirstPublication No. 2010-002870, Japanese Unexamined Patent Application,First Publication No. 2010-032994, Japanese Unexamined PatentApplication, First Publication No. 2010-277043, Japanese UnexaminedPatent Application, First Publication No. 2011-13569, and JapaneseUnexamined Patent Application, First Publication No. 2011-128226 can beused.

Specific examples of the component (F) include polymers having astructural unit (f1) represented by general formula (f1-1) shown below.As the polymer, a polymer (homopolymer) consisting of a structural unit(f1) represented by formula (f1-1) shown below; a copolymer of astructural unit (f1) represented by formula (f1-1) shown below and theaforementioned structural unit (a1); and a copolymer of a structuralunit (f1) represented by formula (f1-1) shown below, a structural unitderived from acrylic acid or methacrylic acid and the aforementionedstructural unit (a1) are preferable. As the structural unit (a1) to becopolymerized with a structural unit (f1) represented by formula (f1-1)shown below, a structural unit derived from1-ethyl-1-cyclooctyl(meth)acrylate or a structural unit represented bythe aforementioned formula (a1-2-01) is preferable.

In the formula, R is the same as defined above; Rf¹⁰² and Rf¹⁰³ eachindependently represents a hydrogen atom, a halogen atom, an alkyl groupof 1 to 5 carbon atoms, or a halogenated alkyl group of 1 to 5 carbonatoms, provided that Rf¹⁰² and Rf¹⁰³ may be the same or different; nf¹represents an integer of 1 to 5; and Rf¹⁰¹ represents an organic groupcontaining a fluorine atom.

In formula (f1-1), R is the same as defined above. As R, a hydrogen atomor a methyl group is preferable.

In formula (f1-1), examples of the halogen atom for Rf¹⁰² and Rf¹⁰³include a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is particularly desirable. Examples of thealkyl group of 1 to 5 carbon atoms for Rf¹⁰² and Rf¹⁰³ include the samealkyl group of 1 to 5 carbon atoms as those described above for R, and amethyl group or an ethyl group is preferable. Specific examples of thehalogenated alkyl group of 1 to 5 carbon atoms represented by Rf¹⁰² orRf¹⁰³ include groups in which part or all of the hydrogen atoms of theaforementioned alkyl groups of 1 to 5 carbon atoms have been substitutedwith halogen atoms. Examples of the halogen atom include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is particularly desirable. Among these, as Rf¹⁰² and Rf¹⁰³, ahydrogen atom, a fluorine atom or an alkyl group of 1 to 5 carbon atomsis preferable, and a hydrogen atom, a fluorine atom, a methyl group oran ethyl group is more preferable.

In formula (f1-1), nf¹ represents an integer of 1 to 5, preferably aninteger of 1 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branchedor cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to15 carbon atoms, and most preferably 1 to 10 carbon atoms.

It is preferable that the hydrocarbon group having a fluorine atom has25% or more of the hydrogen atoms within the hydrocarbon groupfluorinated, more preferably 50% or more, and most preferably 60% ormore, as the hydrophobicity of the resist film during immersion exposureis enhanced.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group of 1 to 5 carbonatoms is preferable, and a methyl group, —CH₂—CF₃, —CH₂—CF₂—CF₃,—CH(CF₃)₂, —CH₂—CH₂—CF₃, and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ are mostpreferable.

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (F)is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and mostpreferably 10,000 to 30,000. When the weight average molecular weight isno more than the upper limit of the above-mentioned range, the resistcomposition exhibits a satisfactory solubility in a resist solvent. Onthe other hand, when the weight average molecular weight is at least aslarge as the lower limit of the above-mentioned range, dry etchingresistance and the cross-sectional shape of the resist pattern becomessatisfactory.

Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

As the component (F), one type may be used alone, or two or more typesmay be used in combination.

The component (F) is typically used in an amount within a range from 0.5to 10 parts by weight, relative to 100 parts by weight of the component(A).

If desired, other miscible additives can also be added to the resistcomposition of the present invention. Examples of such miscibleadditives include additive resins for improving the performance of theresist film, dissolution inhibitors, plasticizers, stabilizers,colorants, halation prevention agents, and dyes.

[Component (S)]

The resist composition for immersion exposure according to the presentinvention can be prepared by dissolving the materials for the resistcomposition in an organic solvent (hereafter, frequently referred to as“component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to give a uniform solution, and one or more kindsof any organic solvent can be appropriately selected from those whichhave been conventionally known as solvents for a chemically amplifiedresist.

Examples thereof include lactones such as γ-butyrolactone; ketones suchas acetone, methyl ethyl ketone (MEK), cyclohexanone, methyl-n-pentylketone (2-heptanone) and methyl isopentyl ketone; polyhydric alcohols,such as ethylene glycol, diethylene glycol, propylene glycol anddipropylene glycol; compounds having an ester bond, such as ethyleneglycol monoacetate, diethylene glycol monoacetate, propylene glycolmonoacetate, and dipropylene glycol monoacetate; polyhydric alcoholderivatives including compounds having an ether bond, such as amonoalkylether (e.g., monomethylether, monoethylether, monopropyletheror monobutylether) or monophenylether of any of these polyhydricalcohols or compounds having an ester bond (among these, propyleneglycol monomethyl ether acetate (PGMEA) and propylene glycol monomethylether (PGME) are preferable); cyclic ethers such as dioxane; esters suchas methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate,butyl acetate, methyl pyruvate, ethyl pyruvate, methylmethoxypropionate, and ethyl ethoxypropionate; aromatic organic solventssuch as anisole, ethylbenzylether, cresylmethylether, diphenylether,dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

These solvents can be used individually, or in combination as a mixedsolvent.

Among these, PGMEA, PGME, γ-butyrolactone and EL are preferable.

Further, among the mixed solvents, a mixed solvent obtained by mixingPGMEA with a polar solvent is preferable. The mixing ratio (weightratio) of the mixed solvent can be appropriately determined, taking intoconsideration the compatibility of the PGMEA with the polar solvent, butis preferably in the range of 1:9 to 9:1, more preferably from 2:8 to8:2.

Specifically, when EL or cyclohexanone is mixed as the polar solvent,the PGMEA:EL or cyclohexanone weight ratio is preferably from 1:9 to9:1, and more preferably from 2:8 to 8:2. Alternatively, when PGME ismixed as the polar solvent, the PGMEA:PGME weight ratio is preferablyfrom 1:9 to 9:1, more preferably from 2:8 to 8:2, and still morepreferably 3:7 to 7:3.

Further, as the component (S), a mixed solvent of at least one of PGMEAand EL with γ-butyrolactone is also preferable. The mixing ratio(former:latter) of such a mixed solvent is preferably from 70:30 to95:5.

The amount of the component (S) is not particularly limited, and isappropriately adjusted to a concentration which enables coating of acoating solution to a substrate In general, the organic solvent is usedin an amount such that the solid content of the resist compositionbecomes within the range from 1 to 20% by weight, and preferably from 2to 15% by weight.

<<Compound>> <<First Compound>>

The compound (B11) according to the present invention is represented bygeneral formula (B11) shown below.

In formula (B11), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group, an alkyl group or analkenyl group, provided that Rb² and Rb³ may be mutually bonded to forma ring with the sulfur atom; and X11⁻ is a counteranion represented byany one of formulae (b11-1) to (b11-3).

In formulae (b11-1) to (b11-3), Rb¹⁰¹, Rb¹⁰⁴ and Rb¹⁰⁵ eachindependently represents a cyclic group which may have a substituent ora chain-like alkenyl group which may have a substituent; Rb¹⁰⁶ to Rb¹⁰⁸each independently represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent; provided thatRb¹⁰⁴ and Rb¹⁰⁵ may be mutually bonded to form a ring; Rb¹⁰⁶ and Rb¹⁰⁷may be mutually bonded to form a ring; Rb¹⁰² represents a fluorine atomor a fluorinated alkyl group of 1 to 5 carbon atoms; Yb¹⁰¹ represents asingle bond or a divalent linking group containing an oxygen atom; Vb¹⁰¹to Vb¹⁰³ each independently represents a single bond, an alkylene groupor a fluorinated alkylene group; L¹⁰¹ and L¹⁰² each independentlyrepresents a single bond or an oxygen atom; Lb¹⁰³ to Lb¹⁰⁵ eachindependently represents a single bond, —CO— or —SO₂—.

In general formula (B11), Rb¹, Rb² and Rb³ are the same as defined forRb¹, Rb² and Rb³ in the aforementioned general formula (m0).

In general formula (B11), X11⁻ is a counteranion represented by any oneof formulae (b11-1) to (b11-3).

In formulae (b11-1) to (b11-3), Rb¹⁰¹, Rb¹⁰⁴ and Rb¹⁰⁵ eachindependently represents a cyclic group which may have a substituent ora chain-like alkenyl group which may have a substituent;

The cyclic group which may have a substituent or the chain-like alkenylgroup represented by Rb¹⁰¹, Rb¹⁰⁴ or Rb¹⁰⁵ is the same as defined forthe cyclic group which may have a substituent or the chain-like alkenylgroup represented by R¹⁰¹, R¹⁰⁴ or R¹⁰⁵ in the aforementioned generalformulae (b-1) to (b-3).

In formula (b11-3), Rb¹⁰⁶ to Rb¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent. The cyclic group which may have a substituent, thechain-like alkyl group which may have a substituent or the chain-likealkenyl group which may have a substituent represented by any of Rb¹⁰⁶to Rb¹⁰⁸ is the same as defined for the cyclic group which may have asubstituent, the chain-like alkyl group which may have a substituent orthe chain-like alkenyl group which may have a substituent represented byany of R¹⁰⁶ to R¹⁰⁸ in the aforementioned general formulae (b-1) to(b-3).

Rb¹⁰⁴ and Rb¹⁰⁵ may be mutually bonded to form a ring.

Rb¹⁰⁶ and Rb¹⁰⁷ may be mutually bonded to form a ring.

Rb¹⁰² represents a fluorine atom or a fluorinated alkyl group of 1 to 5carbon atoms;

Yb¹⁰¹ represents a single bond or a divalent linking group containing anoxygen atom. The single bond or the divalent linking group containing anoxygen atom represented by Yb¹⁰¹ is the same as defined for the singlebond or the divalent linking group containing an oxygen atom representedby Y¹⁰¹ in the aforementioned general formulae (b-1) to (b-3).

Vb¹⁰¹ to Vb¹⁰³ each independently represents a single bond, an alkylenegroup or a fluorinated alkylene group. The single bond, an alkylenegroup or a fluorinated alkylene group represented by any of Vb¹⁰¹ toVb¹⁰³ is the same as defined for the single bond, an alkylene group or afluorinated alkylene group represented by any of V¹⁰¹ to V¹⁰³ in theaforementioned general formulae (b-1) to (b-3).

Lb¹⁰¹ and Lb¹⁰² each independently represents a single bond or an oxygenatom.

Lb¹⁰³ to Lb¹⁰⁵ each independently represents a single bond, —CO— or—SO₂—.

Specific examples of the compound (B11) are shown below.

The compound (B11) may be produced by a production method describedbelow.

In the above reaction formula, A represents a halogen atom; X′11⁻represents Cl⁻ or a trifluoromethanesulfonate anion; MX represents asalt containing an alkali metal cation (such as a lithium ion, a sodiumion or a potassium ion) or an ammonium cation (which may have asubstituent) and a counteranion represented by any one of formulae(b11-1) to (b11-3).

Rb¹, Rb², Rb³ and X11⁻ are the same as defined in the aforementionedformula (B11).

For example, as shown above, X′11⁻ can be changed to the anion (X11⁻) ofthe compound (B11) by a double decomposition reaction.

In the above reaction formula, the first reaction may be conducted inthe absence of a solvent, or in an organic solvent (a typical solventused in Grignard reaction, such as tetrahydrofuran, chloroform ordichloromethane) if desired. The reaction temperature depends on theboiling point of the solvent used, but is about −20 to 150° C. Thereaction time is about 1 hour to several tens of hours.

The second reaction may be conducted in succession to the firstreaction, or conducted after separating the precursor (and purifying ifdesired). The precursor and the aqueous solution of the salt (MX11) aremixed together and stirred, so as to effect a double decompositionreaction. Then, the precipitated solid is separated by filtration, orthe separated oily substance is extracted with an organic solvent toremove the organic solvent, thereby obtaining the compound (B11) in theform of a solid or a viscous liquid. The obtained solid or viscousliquid may be washed with an appropriate organic solvent, or purified byrecrystallization or column chromatography.

The chemical structure of the compound (B11) can be identified by ageneral analytical method (e.g., ¹H—, ¹¹B—, ¹³C—, ¹⁹F—, ³¹P-nuclearmagnetic resonance spectroscopy, infrared spectroscopy and/or elementalanalysis).

<<Polymeric Compound>> <<First Compound>>

The polymeric compound (A0-B11) (hereafter, referred to as “component(A0-B11)” includes a structural unit derived from a compound (B11-01)shown below (hereafter, referred to as “structural unit (a0-b11)”).

In formula (B11-01), Rb¹ represents an electron withdrawing group; Rb²and Rb³ each independently represents an aryl group, an alkyl group oran alkenyl group, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X11-1⁻ is a counteranionrepresented by any one of formulae (b11-01-1) to (b1-01-3).

In formulae (b11-01-1) to (b11-01-3),

Rb²⁰¹ represents a chain-like alkenyl group which may have asubstituent;

Rb²⁰⁴ and Rb²⁰⁵ each independently represents a cyclic group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent (provided that at least one of Rb²⁰⁴ and Rb²⁰⁵ represents achain-like alkenyl group which may have a substituent);

Rb²⁰⁶ to Rb²⁰⁸ each independently represents a cyclic group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent(provided that at least one of Rb²⁰⁶ to Rb²⁰⁸ represents a chain-likealkenyl group which may have a substituent);

Rb¹⁰² represents a fluorine atom or a fluorinated alkyl group of 1 to 5carbon atoms; Yb¹⁰¹ represents a single bond or a divalent linking groupcontaining an oxygen atom; Vb¹⁰¹ to Vb¹⁰³ each independently representsa single bond, an alkylene group or a fluorinated alkylene group; L¹⁰¹and L¹⁰² each independently represents a single bond or an oxygen atom;Lb¹⁰³ and Lb¹⁰⁵ each independently represents a single bond, —CO— or—SO₂—.

In formula (B11-01), Rb¹, Rb² and Rb³ are the same as defined for Rb¹,Rb² and Rb³ in the aforementioned general formula (m0).

Rb²⁰¹ represents a chain-like alkenyl group which may have asubstituent, and is the same as defined for the alkenyl group which mayhave a substituent represented by R¹⁰¹.

Rb²⁰⁴ and Rb²⁰⁵ each independently represents a cyclic group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent (provided that at least one of Rb²⁰⁴ and Rb²⁰⁵ represents achain-like alkenyl group which may have a substituent);

Rb²⁰⁶ to Rb²⁰⁸ each independently represents a cyclic group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent(provided that at least one of Rb²⁰⁶ to Rb²⁰⁸ represents a chain-likealkenyl group which may have a substituent);

Rb¹⁰², Yb¹⁰¹, Vb¹⁰¹ to Vb¹⁰³, L¹⁰¹, L¹⁰² and Lb¹⁰³ to Lb¹⁰⁵ are the sameas defined above.

In formulae (b11-01-1) to (b11-01-3), in the case where at least one ofRb²⁰¹, Rb²⁰⁴ and Rb²⁰⁵, and at least one of Rb²⁰⁶ to Rb²⁰⁸ is achain-like alkenyl group which may have a substituent, (CH₃)C═CH— (apropenyl group) or H₂C═CH— (a vinyl group) is preferable. In the case ofa chain-like alkenyl group which may have a substituent, the vinyl groupor the propenyl group preferably has a divalent group bonded thereto.Examples of the divalent group include an ester bond, an ether bond, anamide bond, a urethane bond, an alkylene group, a (poly)cycloalkylenegroup, a fluorinated alkylene group, an arylene group, or a combinationthereof.

Examples of the structural unit (a0-b11) include a structural unitrepresented by any of general formulae (a0-b11-1) to (a0-b11-3) shownbelow.

In the formulae, R^(α), Rb¹, Rb², Rb³, Rb¹⁰⁵, Rb¹⁰⁶, Rb¹⁰⁸, Yb¹⁰¹, Vb¹⁰¹to Vb¹⁰³, L¹⁰¹, L¹⁰, Lb¹⁰³ to Lb¹⁰⁵ are the same as defined above; andL¹¹ to L¹³ each independently represents a single bond or a divalentlinking group.

In the formulae, L¹¹ to L¹³ are preferably a single bond or a divalentlinking group, more preferably an ester bond, an alkylene group of 1 to10 carbon atoms, a (poly)cycloalkylene group of 5 to 30 carbon atoms, anarylene group of 6 to 10 carbon atoms, or a combination thereof.

Specific examples of the structural units (a0-b11-1) to (a0-b11-3)include the structural units described above as specific examples of thestructural unit (a6) in which the cation moiety has been replaced by anyof the formulae (a0-b11-1) to (a0-b11-3).

As the structural unit (a0-b11) contained in the component (A0-B11), 1type of structural unit may be used, or 2 or more types may be used.

As the structural unit (a0-b11), a structural unit represented bygeneral formula (a0-b11-1) or (a0-b11-2) is preferable.

The amount of the structural unit (a0-b11) within the component (A0-B11)based on the combined total of all structural units constituting thecomponent (A0-B11) is preferably 0.5 to 30 mol %, more preferably 1 to20 mol %, and still more preferably 1.5 to 15 mol %.

When the amount of the structural unit (a0-b11) is at least as large asthe lower limit of the above-mentioned range, the effects of the presentinvention can be enhanced. In addition, it is presumed that thesolubility in a solvent and sensitivity are also improved. On the otherhand, when the amount of the structural unit (a0-b11) is no more thanthe upper limit of the above-mentioned range, a good balance can beachieved with the other structural units, and the lithography propertiescan be improved.

The component (A0-B11) may include other structural units. Examples ofthe other structural units include the aforementioned structural units(a1), (a2), (a3), (a4) and (a6). Further, the component (A0-B11) mayinclude a structural unit (a0-d11) described later.

The component (A0-B11) is preferably a copolymer including a structuralunit (a0-b11) and a structural unit (a1). The copolymer containing thestructural units (a0-b11) and (a1) is preferably a copolymer furthercontaining a structural unit (a2) or (a3), and still more preferably acopolymer containing the structural units (a0-b11), (a1), (a2) and (a3).

In the present invention, the weight average molecular weight (Mw) (thepolystyrene equivalent value determined by gel permeationchromatography) of the component (A0-B11) is not particularly limited,but is preferably 1,000 to 50,000, more preferably 1,500 to 30,000, andmost preferably 2,000 to 20,000. When the weight average molecularweight is no more than the upper limit of the above-mentioned range, theresist composition exhibits a satisfactory solubility in a resistsolvent. On the other hand, when the weight average molecular weight isat least as large as the lower limit of the above-mentioned range, dryetching resistance and the cross-sectional shape of the resist patternbecomes satisfactory.

Further, the dispersity (Mw/Mn) of the component (A0-B11) is notparticularly limited, but is preferably 1.0 to 5.0, more preferably 1.0to 3.0, and most preferably 1.2 to 2.5. Here, Mn is the number averagemolecular weight.

<<Fourth Resist Composition>>

The fourth resist composition of the present embodiment includes theaforementioned polymeric compound (A0-B11). The fourth resistcomposition of the present embodiment may include the components (A),(B), (D), (E), (F) and/or (S), and preferably includes the component(D). The component (D) preferably included in the fourth resistcomposition preferably contains a compound (D0) represented by theaforementioned general formula (d0).

In the fourth resist composition, as the component (A0-B11), one typemay be used, or two or more types of compounds may be used incombination. The component (A0-B11) may be used as a base component oran additive component.

In the case where the component (A0-B11) is used as the base component,the amount of the component (A0-B11) based on the total weight of thecomponent (A) is preferably 25% by weight or more, more preferably 50%by weight or more, still more preferably 75% by weight or more, and maybe even 100% by weight. When the amount is 25% by weight or more, theeffects of the present invention are improved. In addition, it ispresumed that the solubility in a solvent and sensitivity are alsoimproved. In the case where the component (A0-B11) is used as anadditive, the amount of the component (A0-B11) relative to 100 parts byweight of the component (A) is preferably 0.5 to 20 parts by weight.

<<Compound>>

The second compound according to the present embodiment is the compound(D11) shown below.

In formula (D11), Rb¹ represents an electron withdrawing group; Rb² andRb³ each independently represents an aryl group, an alkyl group or analkenyl group, provided that Rb² and Rb³ may be mutually bonded to forma ring with the sulfur atom; and X21⁻ is a counteranion represented byany one of formulae (d11-1) to (d11-3).

In formula (d11-1), Rd¹⁰ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent;

In formula (d1-2), Rd²⁰ represents a chain-like alkenyl group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or an aliphatic cyclic group which may have a substituent(provided that 10-camphorsulfonate is excluded from formula (d11-2));

in formula (d11-3), Rd³⁰ and Rd⁴⁰ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent;

provided that, the carbon atom adjacent to the S atom within the Rd²⁰group in formula (d11-2) has no fluorine atom bonded thereto; Yd¹⁰represents a single bond or a divalent linking group.

In formula (D11), Rb¹, Rb² and Rb³ are the same as defined for Rb¹, Rb²and Rb³ in the aforementioned general formula (m0).

In formula (D11), X21⁻ is a counteranion represented by any one offormulae (d11-1) to (d11-3).

In formula (d11-1), Rd¹⁰ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for Rd¹.

In formula (d11-2), Rd²⁰ represents a chain-like alkenyl group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or an aliphatic cyclic group which may have a substituent(provided that 10-camphorsulfonate is excluded from formula (d11-2)),and is the same as defined for Rd²;

provided that, the carbon atom adjacent to the S atom within the Rd²⁰group in formula (d11-2) has no fluorine atom bonded thereto;

In formula (d11-3), Rd³⁰ and Rd⁴⁰ represents a cyclic group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent,and is the same groups as those defined above for Rd³ and Rd⁴.

Yd¹⁰ represents a single bond or a divalent linking group, and is thesame as defined for Yd¹.

Specific examples of the compound (D11) are shown below.

The compound (D11) may be produced by a production method describedbelow.

In the reaction formula, the compound (X′21) of formula (2) is an acidderived from a counteranion represented by any one of formulae (d11-1)to (d11-3) (a compound in which H⁺ is added to an anion grouprepresented by any one of formulae (d11-1) to (d11-3)).

Rb¹, Rb², Rb³, X11⁻ and X21⁻ are the same as defined in theaforementioned formula

(B11) or (D11).

In the above reaction, the method for reacting the compound (B11) withthe compound (2) to obtain the compound (D11) is not particularlylimited, but can be performed, for example, by dissolving the compound(2) in a suitable organic solvent and water in the presence of asuitable alkali metal hydroxide, followed by addition of the compound(B11) and stirring.

The alkali metal hydroxide used in the above reaction is notparticularly limited, and examples thereof include sodium hydroxide andpotassium hydroxide. Alternatively, an ammonium hydroxide such as TMAH(which may have a substituent) may be used.

Examples of the organic solvent usable in the above reaction includedichloromethane, chloroform and ethyl acetate.

In the above reaction, the reaction time depends on the reactivity ofthe compounds (B11) and (2), the reaction temperature or the like.However, in general, the reaction time is preferably 0.5 to 80 hours.

The reaction temperature in the above reaction is preferably 20 to 200°C.

After the reaction, the compound (D11) contained in the reaction mixturemay be separated and purified. Like in the case of the compound (B11),the separation and purification can be conducted by a conventionalmethod. For example, any one of concentration, solvent extraction,distillation, crystallization, recrystallization and chromatography canbe used alone, or two or more of these methods may be used incombination.

Like in the case of the compound (B11), the chemical structure of thecompound (D11) can be identified by a general method.

<<Polymeric Compound>>

<Second Polymeric Compound>

The polymeric compound (A0-D11) (hereafter, referred to as “component(A0-D11)” includes a structural unit derived from a compound (D11-01)shown below (hereafter, referred to as “structural unit (a0-d11)”).

In formula (D11-01), Rb¹ represents an electron withdrawing group; Rb²and Rb³ each independently represents an aryl group, an alkyl group oran alkenyl group, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X21-1⁻ is a counteranionrepresented by any one of formulae (d11-01-1) to (d11-01-3);

in formula (d11-01-1), Rd¹⁰⁰ represents a chain-like alkenyl group whichmay have a substituent;

in formula (d11-01-2), Rd²⁰⁰ represents a chain-like alkenyl group whichmay have a substituent;

in formula (d11-01-3), at least one of Rd³⁰⁰ and Rd⁴⁰⁰ represents achain-like alkenyl group which may have a substituent;

provided that, the carbon atom adjacent to the S atom within the Rd²⁰⁰group in formula (d11-01-2) has no fluorine atom bonded thereto; Yd¹⁰represents a single bond or a divalent linking group.

In formula (D11-01), Rb¹, Rb² and Rb³ are the same as defined for Rb¹,Rb² and Rb³ in the aforementioned general formula (m0).

In formula (D11-01), X21⁻ is a counteranion represented by any one offormulae (d11-01-1) to (d11-01-3).

in formula (d11-01-1), Rd¹⁰⁰ represents a chain-like alkenyl group whichmay have a substituent;

in formula (d11-01-2), Rd²⁰⁰ represents a chain-like alkenyl group whichmay have a substituent;

in formula (d11-01-3), at least one of Rd³⁰⁰ and Rd⁴⁰⁰ represents achain-like alkenyl group which may have a substituent;

provided that, the carbon atom adjacent to the S atom within the Rd²⁰⁰group in formula (d11-2) has no fluorine atom bonded thereto; Yd¹⁰represents a single bond or a divalent linking group.

In formulae (d11-01-1) to (d11-01-3), in the case where at least one ofRd¹⁰⁰, Rd²⁰⁰, Rd³⁰⁰ and Rd⁴⁰⁰ is a chain-like alkenyl group which mayhave a substituent, (CH₃)C═CH— (a propenyl group) or H₂C═CH— (a vinylgroup) is preferable. In the case of a chain-like alkenyl group whichmay have a substituent, the vinyl group or the propenyl group preferablyhas a divalent group bonded thereto. Examples of the divalent groupinclude an ester bond, an ether bond, an amide bond, a urethane bond, analkylene group, a (poly)cycloalkylene group, an arylene group, or acombination thereof.

Examples of the structural unit (a0-d11) include a structural unitrepresented by any of general formulae (a0-d11-1) to (a0-d11-3) shownbelow.

In the formulae, R^(α), Rb¹, Rb², Rb³, Rd¹⁰, Rd²⁰, Rd³⁰, Rd⁴⁰ and Yd¹⁰are the same as defined above; L¹ to L³ each independently represents asingle bond or a divalent linking group.

In the formulae, L¹ to L³ are preferably a single bond or a divalentlinking group, more preferably an ester bond, an alkylene group of 1 to10 carbon atoms, a (poly)cycloalkylene group of 5 to 30 carbon atoms, anarylene group of 6 to 10 carbon atoms, or a combination thereof.

As the structural unit (a0-d11) contained in the component (A0-D11), 1type of structural unit may be used, or 2 or more types may be used.

The amount of the structural unit (a0-d11) within the component (A0-D11)based on the combined total of all structural units constituting thecomponent (A0-D11) is preferably 0.5 to 30 mol %, more preferably 1 to20 mol %, and still more preferably 1.5 to 15 mol %.

When the amount of the structural unit (a0-d11) is at least as large asthe lower limit of the above-mentioned range, the effects of the presentinvention can be enhanced. In addition, it is presumed that thesolubility in a solvent is also improved. On the other hand, when theamount of the structural unit (a6) is no more than the upper limit ofthe above-mentioned range, a good balance can be achieved with the otherstructural units, and the lithography properties can be improved.

The component (A0-D11) may include other structural units. Examples ofthe other structural units include the aforementioned structural units(a1), (a2), (a3), (a4) and (a6). Further, the component (A0-D11) mayinclude the aforementioned structural unit (a0-b11).

The component (A0-D11) is preferably a copolymer including a structuralunit (a0-d11) and a structural unit (a1). The copolymer containing thestructural units (a0-d11) and (a1) is preferably a copolymer furthercontaining a structural unit (a2) or (a3), and still more preferably acopolymer containing the structural units (a0-d11), (a1), (a2) and (a3).

In the present invention, the weight average molecular weight (Mw) (thepolystyrene equivalent value determined by gel permeationchromatography) of the component (A0-D11) is not particularly limited,but is preferably 1,000 to 50,000, more preferably 1,500 to 30,000, andmost preferably 2,000 to 20,000. When the weight average molecularweight is no more than the upper limit of the above-mentioned range, theresist composition exhibits a satisfactory solubility in a resistsolvent. On the other hand, when the weight average molecular weight isat least as large as the lower limit of the above-mentioned range, dryetching resistance and the cross-sectional shape of the resist patternbecomes satisfactory.

Further, the dispersity (Mw/Mn) of the component (A0-D11) is notparticularly limited, but is preferably 1.0 to 5.0, more preferably 1.0to 3.0, and most preferably 1.2 to 2.5. Here, Mn is the number averagemolecular weight.

(Production Method of First and Second Polymeric Compound)

The polymeric compounds according to the third and sixth embodiment canbe obtained by a conventional polymerization method, for example,dissolving the monomers corresponding with each of the structural unitsin a polymerization solvent, followed by addition of a radicalpolymerization initiator such as azobisisobutyronitrile (AIBN) (e.g.,V-601).

<<Fifth Resist Composition>>

The fifth resist composition of the present embodiment includes theaforementioned polymeric compound (A0-D11). The fifth resist compositionof the present embodiment may include the components (A), (B), (D), (E),(F) and/or (S), and preferably includes the component (B). The component(B) preferably included in the fifth resist composition preferablycontains a compound (B0) represented by the aforementioned generalformula (b0).

In the fifth resist composition, as the component (A0-D11), one type maybe used, or two or more types of compounds may be used in combination.The component (A0-D11) may be used as a base component or an additivecomponent.

In the case where the component (A0-D11) is used as the base component,the amount of the component (A0-D11) based on the total weight of thecomponent (A) is preferably 25% by weight or more, more preferably 50%by weight or more, still more preferably 75% by weight or more, and maybe even 100% by weight. When the amount is 25% by weight or more, theeffects of the present invention are improved. In addition, it ispresumed that the solubility in a solvent is also improved. In the casewhere the component (A0-D11) is used as an additive, the amount of thecomponent (A0-D11) relative to 100 parts by weight of the component (A)is preferably 0.5 to 20 parts by weight.

The resist composition of the present invention includes a compound orpolymeric compound containing a cation moiety having an electronwithdrawing group on a specific bonding position (meta position) andexhibiting an excellent solubility in a solvent. As a result, the resistcomposition exhibits excellent lithography properties such as Eop, ELmargin, MEEF and LWR.

<<Method of Forming a Resist Pattern>>

The method of forming a resist pattern according to an eighth aspect ofthe present invention includes: forming a resist film on a substrateusing a resist composition of the present invention; conducting exposureof the resist film; and developing the resist film to form a resistpattern.

The method for forming a resist pattern according to the presentinvention can be performed, for example, as follows.

Firstly, a resist composition of the present invention is applied to asubstrate using a spinner or the like, and a bake treatment (postapplied bake (PAB)) is conducted at a temperature of 80 to 150° C. for40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.

Following selective exposure of the thus formed resist film, either byexposure through a mask having a predetermined pattern formed thereon(mask pattern) using an exposure apparatus such as an ArF exposureapparatus, an electron beam lithography apparatus or an EUV exposureapparatus, or by patterning via direct irradiation with an electron beamwithout using a mask pattern, baking treatment (post exposure baking(PEB)) is conducted under temperature conditions of 80 to 150° C. for 40to 120 seconds, and preferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment.

The developing treatment is conducted using an alkali developingsolution in the case of an alkali developing process, and a developingsolution containing an organic solvent (organic developing solution) inthe case of a solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. The rinse treatment is preferably conducted using pure waterin the case of an alkali developing process, and a rinse solutioncontaining an organic solvent in the case of a solvent developingprocess.

In the case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. If desired, bake treatment (post bake) can be conductedfollowing the developing. In this manner, a resist pattern can beobtained.

The substrate is not specifically limited and a conventionally knownsubstrate can be used. For example, substrates for electroniccomponents, and such substrates having wiring patterns formed thereoncan be used. Specific examples of the material of the substrate includemetals such as silicon wafer, copper, chromium, iron and aluminum; andglass. Suitable materials for the wiring pattern include copper,aluminum, nickel, and gold.

Further, as the substrate, any one of the above-mentioned substratesprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic antireflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a “multilayer resist method” is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper resist film) are provided on a substrate, and aresist pattern formed on the upper resist film is used as a mask toconduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is broadly classified into a method inwhich a double-layer structure consisting of an upper-layer resist filmand a lower-layer organic film is formed (double-layer resist method),and a method in which a multilayer structure having at least threelayers consisting of an upper-layer resist film, a lower-layer organicfilm and at least one intermediate layer (thin metal film or the like)provided between the upper-layer resist film and the lower-layer organicfilm (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiation such as ArF excimer laser,KrF excimer laser, F₂ excimer laser, extreme ultraviolet rays (EUV),vacuum ultraviolet rays (VUV), electron beam (EB), X-rays, and softX-rays. The resist composition of the present invention is effective toKrF excimer laser, ArF excimer laser, EB and EUV.

The exposure of the resist film can be either a general exposure (dryexposure) conducted in air or an inert gas such as nitrogen, orimmersion exposure (immersion lithography).

In immersion lithography, the region between the resist film and thelens at the lowermost point of the exposure apparatus is pre-filled witha solvent (immersion medium) that has a larger refractive index than therefractive index of air, and the exposure (immersion exposure) isconducted in this state.

The immersion medium preferably exhibits a refractive index larger thanthe refractive index of air but smaller than the refractive index of theresist film to be exposed. The refractive index of the immersion mediumis not particularly limited as long as it satisfies the above-mentionedrequirements.

Examples of this immersion medium which exhibits a refractive index thatis larger than the refractive index of air but smaller than therefractive index of the resist film include water, fluorine-based inertliquids, silicon-based solvents and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃,C₄F₉OC₂H or C₅H₃F₇ as the main component, which have a boiling pointwithin a range from 70 to 180° C. and preferably from 80 to 160° C. Afluorine-based inert liquid having a boiling point within theabove-mentioned range is advantageous in that the removal of theimmersion medium after the exposure can be conducted by a simple method.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly desirable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, one example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by weight aqueous solution oftetramethylammonium hydroxide (TMAH) can be given.

As the organic solvent contained in the organic developing solution usedin a solvent developing process, any of the conventional organicsolvents can be used which are capable of dissolving the component (A)(prior to exposure). Specific examples of the organic solvent includepolar solvents such as ketone solvents, ester solvents, alcoholsolvents, amide solvents and ether solvents, and hydrocarbon solvents.

If desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant can be used.

When a surfactant is added, the amount thereof based on the total amountof the organic developing solution is generally 0.001 to 5% by weight,preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% byweight.

The developing treatment can be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the substrate by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the substrate (spray method),and a method in which the developing solution is continuously ejectedfrom a developing solution ejecting nozzle while scanning at a constantrate to apply the developing solution to the substrate while rotatingthe substrate at a constant rate (dynamic dispense method).

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe substrate while rotating it at a constant rate (rotational coatingmethod), a method in which the substrate is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the substrate (spray method).

EXAMPLES

The present invention will be described more specifically with referenceto the following examples, although the scope of the present inventionis by no way limited by these examples.

Compound Synthesis Example [Synthesis of Compound 1](1) Synthesis of3-fluorophenymagnesium bromide

To a reaction vessel purged with nitrogen was added 28.0 parts by weightof magnesium and 62.0 parts by weight of tetrahydrofuran was addedthereto. Separately, 173 parts by weight of 3-bromofluorobenzene and 330parts by weight of tetrahydrofuran were added to a dropping funnel, andthe content of the dropping funnel was dropwise added to the reactionvessel while maintaining the temperature not to exceed 60° C. After thedropwise addition, the reaction was continued at 40 to 60° C. for 1hour. Then, 710 parts by weight of tetrahydrofuran was added, therebyobtaining a tetrahydrofuran solution of 3-fluorophenylmagnesium bromide.

(2) Synthesis of Objective Compound

To a reaction vessel purged with nitrogen was added 66.3 parts by weightof diphenylsulfoxide, 652 parts by weight of tetrahydrofuran and 510parts by weight of trimethylsilyltrifluoromethanesulfonate, followed bycooling to 5° C. using an ice bath.

Then, the tetrahydrofuran solution of 3-fluorophenylmagnesium bromidesynthesized in (1) was cooled to 5° C. using an ice bath, and dropwiseadded to the reaction vessel using a dropping funnel while maintainingthe temperature not to exceed 15° C. After the dropwise addition, thereaction was continued at 10° C. for 1 hour to complete the reaction.

The resulting solution was added to 3,400 parts by weight of an ionexchange water cooled to 5° C. using an ice bath while maintaining thetemperature not to exceed 15° C. After the addition, the solution wasstirred at a temperature not exceeding 25° C. for 1 hour. Thereafter,3,200 parts by weight of toluene was added, followed by stirring for 1hour. The toluene phase was removed, and the remaining solution waswashed with 1,600 parts by weight of toluene twice. Subsequently, 3,200parts by weight of dichloromethane was added and extracted, followed byseparating the aqueous phase and washing the organic phase with 1,200parts by weight of an ion exchange water 4 times. The solvent wasremoved from the organic phase, and 75.0 parts by weight ofdichloromethane was added to the obtained yellow oily residue, so as todissolve the residue. The obtained solution was gradually added to 1,500parts by weight of diethylether while stirring, so as to precipitate apale yellow solid. The solid was filtered and separated, followed byaddition of 480 parts by weight of dichloromethane to dissolve thesolid. To the resulting solution was gradually added 650 parts by weightof diethylether while stirring, so as to precipitate white needlecrystals. The crystals were separated by filtration, followed by dryingunder reduced pressure, thereby obtaining 114.0 parts by weight ofcompound 1 as an objective compound with a yield of 81% (purity: 99.8%or higher). The product was identified by ¹H-NMR and ¹⁹F-NMR {¹H-NMR,d₆-dimethylsulfoxide, δ(ppm); 7.95-7.70 (13H, m), 7.60 (1H, d)}.{¹⁹F-NMR, d₆-dimethylsulfoxide, δ(ppm); −74 (3F, s), −104 (1F, s);internal standard=hexafluorobenzene, −159 (6F, s)}. The structure of thecompound 1 is shown below.

[Synthesis of Compound 2](1) Synthesis of 3-fluoromethylphenymagnesiumbromide

To a reaction vessel purged with nitrogen was added 19.0 parts by weightof magnesium and 45.0 parts by weight of tetrahydrofuran was addedthereto. Separately, 150 parts by weight of 3-bromobenzotrifluoride and222 parts by weight of tetrahydrofuran were added to a dropping funnel,and the content of the dropping funnel was dropwise added to thereaction vessel while maintaining the temperature not to exceed 60° C.After the dropwise addition, the reaction was continued at 40 to 60° C.for 1 hour. Then, 477 parts by weight of tetrahydrofuran was added,thereby obtaining a tetrahydrofuran solution of3-trifluoromethylphenylmagenesium bromide.

(2) Synthesis of Objective Compound

To a reaction vessel purged with nitrogen was added 45.0 parts by weightof diphenylsulfoxide, 444 parts by weight of tetrahydrofuran and 345parts by weight of trimethylsilyltrifluoromethanesulfonate, followed bycooling to 5° C. using an ice bath. Then, the tetrahydrofuran solutionof 3-trifluoromethylphenylmagenesium bromide synthesized in (1) wascooled to 5° C. using an ice bath, and dropwise added to the reactionvessel using a dropping funnel while maintaining the temperature not toexceed 15° C. After the dropwise addition, the reaction was continued at10° C. for 1 hour to complete the reaction.

The resulting solution was added to 2,400 parts by weight of an ionexchange water cooled to 5° C. using an ice bath while maintaining thetemperature not to exceed 15° C. After the addition, the solution wasstirred at a temperature not exceeding 25° C. for 1 hour. Thereafter,2,300 parts by weight of toluene was added, followed by stirring for 1hour. The toluene phase was removed, and the remaining solution waswashed with 1,150 parts by weight of toluene twice. Subsequently, 2,300parts by weight of dichloromethane was added and extracted, followed byseparating the aqueous phase and washing the organic phase with 850parts by weight of an ion exchange water 4 times. The solvent wasremoved from the organic phase, and 55.0 parts by weight ofdichloromethane was added to the obtained yellow oily residue, so as todissolve the residue. The obtained solution was gradually added to 1,050parts by weight of diethylether while stirring, so as to precipitate apale yellow solid. The solid was filtered and separated, followed byaddition of 350 parts by weight of dichloromethane to dissolve thesolid. To the resulting solution was gradually added 450 parts by weightof diethylether while stirring, so as to precipitate white needlecrystals. The crystals were separated by filtration, followed by dryingunder reduced pressure, thereby obtaining 75.0 parts by weight ofcompound 2 as an objective compound with a yield of 70% (purity: 99.9%or higher). The product was identified by ¹H-NMR and ¹⁹F-NMR {¹H-NMR,d₆-dimethylsulfoxide, δ(ppm); 8.40 (1H, s), 8.20 (1H, d), 8.05-7.70(12H, m)}. {¹⁹F-NMR, d₆-dimethylsulfoxide, δ(ppm); −58 (3F, s), −74 (3F,s); internal standard=hexafluorobenzene, −159 (6F, s)}. The structure ofthe compound 2 is shown below.

[Synthesis of Compound (1)]

10 g of compound 1 was dissolved in 50 g of dichloromethane. Then, 50 gof water and 9.5 g of compound 3 was added, followed by stirring for 30minutes.

Thereafter, the organic solvent phase was subjected to separation with50 g of water, and the washing was conducted 3 times. The obtainedorganic solvent phase was dropwise added to 500 g of hexane over 60minutes, followed by stirring for 30 minutes and filtration. Theobtained powder was dried at room temperature for 12 hours, therebyobtaining 11.5 g of compound (1).

Compound (1)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.78 (m, 1H, CH), 4.66 (t, 1H, CH), 3.88(t, 1H, CH), 3.31-3.36 (m, 1H, CH), 2.47-2.49 (m, 1H, CH), 1.73-2.21 (m,4H, CH₂)

[Synthesis of Compound (7)]

10 g of compound 1 was dissolved in 50 g of dichloromethane, and 5.53 gof compound 4 and 50 g of a 5% aqueous tetramethylammonium hydroxidesolution were added, followed by stirring for 30 minutes. Thereafter,the organic solvent phase was subjected to separation with 50 g ofwater, and the washing was conducted 10 times. The obtained organicsolvent phase was dropwise added to 500 g of diisopropylether over 60minutes, followed by stirring for 30 minutes and filtration.

The obtained powder was dried at room temperature for 12 hours, therebyobtaining 10.16 g of compound (7).

The NMR analysis results are described later.

In the same manner as the compound (1), compounds (2) to (4) and (12) to(14) were synthesized. Further, in the same manner as the compound (7),compounds (5) to (11) and (D1-1) were synthesized. The structures ofcompounds (2) to (14) and (D1-1) and the results of the ¹H-NMR analysisare shown below.

[Results of ¹H-NMR Analysis]

Compound (2)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.55 (t, 2H, CH₂), 1.64-1.96 (m, 15H, Ad)Compound (3)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.40 (t, 2H, CH2), 4.21 (t, 2H, CH₂),1.61-1.98 (m, 15H, Ad)

Compound (4)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 5.46 (t, 1H, oxo-norbornane), 4.97 (s,1H, oxo-norbornane), 4.71 (d, 1H, oxo-norbornane), 4.57 (d, 1H,oxo-norbornane), 2.69-2.73 (m, 1H, oxo-norbornane), 2.06-2.16 (m, 2H,oxo-norbornane)

Compound (5)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.43 (s, 2H, CH₂), 2.01 (s, 3H, CH₃)

Compound (6)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.01 (s, 2H, CH₂), 3.23 (s, 3H, CH₃)

Compound (7)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.55 (s, 2H, CH₂), 1.68-1.98 (m, 15H, Ad)Compound (8)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.12 (s, 2H, CH₂), 2.31-2.43 (m, 1H, CH),1.87-2.02 (m, 2H, CH₂), 1.49-1.68 (m, 1H, CH), 0.85-1.15 (m, 9H,CH₃+CH₃+CH₃)

Compound (9)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 5.70 (t, 1H, CH), 4.46-4.30 (m, 2H, CH₂),3.50 (m, 2H, CH₂), 2.71-2.64 (m, 1H, CH₂), 2.33-2.24 (m, 1H, CH₂)

Compound (10)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.80 (s, 1H, Ad), 3.80 (s, 2H, CH₂), 2.11(d, 2H, Ad), 1.30-1.98 (m, 12H, Ad)

Compound (11)

δ(ppm)=7.50-8.00 (m, 14H, ArH) 4.43 (t, 2H, COOCH₂), 2.81 (m, 2H,Camphanic acid), 2.41 (m, 1H, Camphanic acid), 1.98 (t, 2H, CCH₂SO₃),1.56 (m, 1H, Camphanic acid), 0.79-1.10 (m, 9H, Camphanic acid)

Compound (12)

δ(ppm)=7.50-8.00 (m, 14H, ArH), 6.12 (s, 1H, CH), 5.65 (s, 1H, CH),4.53-4.69 (t, 2H, CH₂), 1.92 (s, 3H, CH₃)

Compound (13)

δ(ppm)=7.50-8.00 (m, 14H, ArH), 6.12 (s, 1H, CH), 5.78 (s, 1H, CH), 4.85(s, 1H, CH), 4.53-4.68 (t, 2H, CH₂), 1.92 (s, 3H, CH₃)

Compound (14)

δ(ppm)=7.50-8.00 (m, 14H, ArH), 6.05 (s, 1H, CH), 5.65 (s, 1H, CH),4.49-4.52 (t, 2H, CH₂), 4.28-4.32 (t, 2H, CH₂), 1.86 (s, 3H, CH₃)

Compound (D1-1)

δ(ppm)=7.50-8.00 (m, 14H, ArH), 2.88 (d, 1H, CH), 2.66-2.74 (m, 1H, CH),2.37 (d, 1H, CH), 2.17-2.24 (m, 1H, CH), 1.90 (t, 1H, CH), 1.74-1.89 (m,2H, CH₂), 1.22-1.29 (m, 2H, CH₂), 1.03 (s, 3H, CH₃), 0.71 (s, 3H, CH₃)

[Synthesis of Compound (15)]

10 g of compound 2 was dissolved in 50 g of dichloromethane. Then, 50 gof water and 8.47 g of compound 3 was added, followed by stirring for 30minutes.

Thereafter, the organic solvent phase was subjected to separation with50 g of water, and the washing was conducted 3 times. The obtainedorganic solvent phase was dropwise added to 500 g of hexane over 60minutes, followed by stirring for 30 minutes and filtration. Theobtained powder was dried at room temperature for 12 hours, therebyobtaining 12.25 g of compound (15).

Compound (15)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.78 (m, 1H, CH), 4.66 (t, 1H, CH), 3.88 (t, 1H, CH), 3.31-3.36 (m, 1H,CH), 2.47-2.49 (m, 1H, CH), 1.73-2.21 (m, 4H, CH₂)

In the same manner as the compound (15), compounds (16) to (18) and (26)to (28) were synthesized. Further, with the exception of changing thecation to that of the compound 2, in the same manner as the compound(7), compounds (19) to (25) and (D1-2) were synthesized. The structuresof compounds (16) to (28) and (D1-2) and the results of the ¹H-NMRanalysis are shown below.

[Results of ¹H-NMR Analysis]

Compound (16)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.55 (t, 2H, CH₂), 1.64-1.96 (m, 15H, Ad)

Compound (17)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.40 (t, 2H, CH₂), 4.21 (t, 2H, CH₂), 1.61-1.98 (m, 15H, Ad)

Compound (18)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, H, ArH), 8.50 (s, 1H, ArH),5.46 (t, 1H, oxo-norbomane), 4.97 (s, 1H, oxo-norbornane), 4.71 (d, 1H,oxo-norbornane), 4.57 (d, 1H, oxo-norbornane), 2.69-2.73 (m, 1H,oxo-norbornane), 2.06-2.16 (m, 2H, oxo-norbornane)

Compound (19)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.43 (s, 2H, CH₂), 2.01 (s, 3H, CH₃)

Compound (20)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.01 (s, 2H, CH₂), 3.23 (s, 3H, CH₃)

Compound (21)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.55 (s, 2H, CH₂), 1.68-1.98 (m, 15H, Ad)

Compound (22)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.12 (s, 2H, CH₂), 2.31-2.43 (m, 1H, CH), 1.87-2.02 (m, 2H, CH₂),1.49-1.68 (m, 1H, CH), 0.85-1.15 (m, 9H, CH₃+CH₃+CH₃)

Compound (23)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),5.70 (t, 1H, CH), 4.46-4.30 (m, 2H, CH₂), 3.50 (m, 2H, CH₂), 2.71-2.64(m, 1H, CH₂), 2.33-2.24 (m, 1H, CH₂)

Compound (24)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.80 (s, 1H, Ad), 3.80 (s, 2H, CH₂), 2.11 (d, 2H, Ad), 1.30-1.98 (m,12H, Ad)

Compound (25)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),4.43 (t, 2H, COOCH₂), 2.81 (m, 2H, Camphanic acid), 2.41 (m, 1H,Camphanic acid), 1.98 (t, 2H, CCH₂SO₃), 1.56 (m, 1H, Camphanic acid),0.79-1.10 (m, 9H, Camphanic acid)

Compound (26)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 6.12 (s, 1H, CH), 5.65 (s, 1H, CH),4.53-4.69 (t, 2H, CH₂), 1.92 (s, 3H, CH₃)

Compound (27)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 6.12 (s, 1H, CH), 5.78 (s, 1H, CH), 4.85(s, 1H, CH), 4.53-4.68 (t, 2H, CH₂), 1.92 (s, 3H, CH₃)

Compound (28)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 6.05 (s, 1H, CH), 5.65 (s, 1H, CH),4.49-4.52 (t, 2H, CH₂), 4.28-4.32 (t, 2H, CH₂), 1.86 (s, 3H, CH₃)

Compound (D1-2)

δ(ppm)=7.74-7.90 (m, 12H, ArH), 8.25 (d, 1H, ArH), 8.50 (s, 1H, ArH),2.88 (d, 1H, CH), 2.66-2.74 (m, 1H, CH), 2.37 (d, 1H, CH), 2.17-2.24 (m,1H, CH), 1.90 (t, 1H, CH), 1.74-1.89 (m, 2H, CH₂), 1.22-1.29 (m, 2H,CH₂), 1.03 (s, 3H, CH₃), 0.71 (s, 3H, CH₃)

Using the obtained compounds, resist compositions were produced with theblend ratio shown in Tables 1 to 3 below (Examples 1 to 10 andComparative Examples 1 to 6).

TABLE 1 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Exxample 1 (A)-1 (B1)-2  (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [7.83] [5.15] [4.0] [0.2] [100] [3300]Comparative (A)-1 (B)-1 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 1 [100][8.00] [5.15] [4.0] [0.2] [100] [3300] Comparative (A)-1 (B)-2 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 Example 2 [100] [8.00] [5.15] [4.0] [0.2] [100][3300] Comparative (A)-1 (B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 3[100] [8.24] [5.15] [4.0] [0.2] [100] [3300] Comparative (A)-1 (B)-4(D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 4 [100] [7.83] [5.15] [4.0] [0.2][100] [3300]

TABLE 2 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 2 (A)-1 (B1)-2 (D1)-1  (F)-1 (E)-1 (S)-1 (S)-2 [100] [7.83] [5.33] [4.0] [0.2] [100][3300] Example 3 (A)-1 (B1)-16 (D1)-2  (F)-1 (E)-1 (S)-1 (S)-2 [100][8.51] [5.85] [4.0] [0.2] [100] [3300] Example 4 (A)-1 (B1)-16 (D1)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [8.51] [5.33] [4.0] [0.2] [100] [3300]Example 5 (A)-1 (B1)-16 (D1)-25 (F)-1 (E)-1 (S)-1 (S)-2 [100] [8.51][6.62] [4.0] [0.2] [100] [3300] Example 6 (A)-1 (B1)-16 (D1)-24 (F)-1(E)-1 (S)-1 (S)-2 [100] [8.51] [6.3]  [4.0] [0.2] [100] [3300]Comparative (A)-1 (B)-1 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 5 [100][8.00] [5.15] [4.0] [0.2] [100] [3300]

TABLE 3 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Comparative (A)-1 (B)-1 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 Example 6 [100] [8.00] [5.15] [4.0] [0.2] [100][3300] Example 7 (A)-1 (B)-1 (D1)-1  (F)-1 (E)-1 (S)-1 (S)-2 [100][8.00] [5.33] [4.0] [0.2] [100] [3300] Example 8 (A)-1 (B)-1 (D1)-2 (F)-1 (E)-1 (S)-1 (S)-2 [100] [8.00] [5.85] [4.0] [0.2] [100] [3300]Example 9 (A)-1 (B)-1 (D1)-25 (F)-1 (E)-1 (S)-1 (S)-2 [100] [8.00][6.62] [4.0] [0.2] [100] [3300] Example 10 (A)-1 (B)-1 (D1)-24 (F)-1(E)-1 (S)-1 (S)-2 [100] [8.00] [6.3]  [4.0] [0.2] [100] [3300]

In the tables, the reference characters indicate the following. Further,the values in brackets [ ] indicate the amount of the component added.

(A)-1: polymeric compound (A)-1 shown below

(B)-1 to (B)-4: compounds (B)-1 to (B)-4 shown below, respectively

(B1)-2, (B1)-16: the above compounds (2) and (16), respectively

(D)-1: compound (D)-1 shown below

(D1)-1, (D1)-2, (D1)-24, (D1)-25: the above compounds (D1)-1, (D1)-2,(D1)-24 and (D1)-25, respectively

(F)-1: polymeric compound (F)-1 shown below (molar ratio: l/m=77/23,Mw=23,100, Mw/Mn=1.78)

(E)-1: salicylic acid

(S)-1: γ-butyrolactone

(S)-2: a mixed solvent of PGMEA/PGME/cyclohexanone=45/30/25 (weightratio)

Formation of Resist Pattern Examples 1 to 10, Comparative Examples 1 to6

Organic anti-reflection film compositions “ARC95” and “ARC212” (bothmanufactured by Brewer Science Ltd.) were applied to an 12-inch siliconwafer using a spinner with a thickness of 72 nm and 14 nm, respectively,and the composition was then baked at 205° C. for 60 seconds and dried,thereby forming an organic anti-reflection film having a film thicknessof 85 nm.

Then, each of the above resist compositions in Tables 1 to 3 was appliedto the antireflection film, and was then prebaked (PAB) on a hotplate at110° C. for 50 seconds and dried, thereby forming a resist film having afilm thickness of 85 nm.

Subsequently, the resist film was selectively irradiated with an ArFexcimer laser (193 nm) through a mask, using an immersion lithographyArF exposure apparatus NSR-S609B (manufactured by Nikon Corporation; NA(numerical aperture)=1.07; Dipole (in/out=0.78/0.97) with Polano;immersion medium: water).

Further, a post exposure bake (PEB) was conducted at 90° C. for 50seconds.

Next, a solvent development was conducted at 23° C. for 13 seconds usingbutyl acetate, followed by drying by shaking.

As a result, in each of the examples, a space and line pattern(hereafter, referred to as “SL pattern”) having a space width of 47 nmand a pitch of 110 nm was formed.

[Evaluation of Optimum Exposure Dose (Eop)]

The optimum exposure dose Eop (mJ/cm²) with which the SL pattern wasformed in the above formation of resist pattern was determined. Theresults are indicated under “Eop” in Tables 4 to 6.

[Evaluation of Exposure Latitude (EL Margin)]

With respect to the exposure dose with which the above SL pattern isformed, the exposure dose with which an SL pattern having a dimension ofabout the target dimension ±5% was determined, and the EL margin (unit:%) was determined by the following formula. The results are indicated“5% EL (%)” in Tables 4 to 6.EL margin(%)=(|E1−E2|/Eop)×100

E1: Exposure dose (mJ/cm²) with which an SL pattern having a line widthof 44.5 nm was formed

E2: Exposure dose (mJ/cm²) with which an SL pattern having a line widthof 49.5 nm was formed

The larger the value of the “EL margin”, the smaller the change in thepattern size by the variation of the exposure dose.

[Evaluation of Mask Error Factor (MEEF)]

In accordance with the same procedure as in the formation of the SLpattern, an SL pattern having a pitch of 110 nm was formed with the sameexposure dose and using a mask pattern in which the target size of theline pattern was 43 to 52 nm (10 target sizes at intervals of 1 nm). Thevalue of the mask error factor was determined as the gradient of a graphobtained by plotting the target size (nm) on the horizontal axis, andthe actual size (nm) of the space pattern formed on the resist filmusing each mask pattern on the vertical axis. A MEEF value (gradient ofthe plotted line) closer to 1 indicates that a resist pattern faithfulto the mask pattern was formed.

The results are shown in Tables 4 to 6.

[Evaluation of Line Width Roughness (LWR)]

With respect to each of the above SL patterns, the space width at 400points in the lengthwise direction of the space were measured using ameasuring scanning electron microscope (SEM) (product name: S-9380,manufactured by Hitachi High-Technologies Corporation; accelerationvoltage: 300V). From the results, the value of 3 times the standarddeviation s (i.e., 3s) was determined, and the average of the 3s valuesat 400 points was calculated as a yardstick of LWR. The results areshown in Tables 4 to 6.

The smaller this 3s value is, the lower the level of roughness of theline width, indicating that an SL pattern with a uniform width wasobtained.

TABLE 4 Eop 5% EL (%) LWR (nm) MEEF (nm) Example 1 16.21 4.65 2.21 1.93Comparative 20.32 3.21 2.62 2.32 Example 1 Comparative 20.12 3.21 2.652.36 Example 2 Comparative 21.35 3.12 2.73 2.29 Example 3 Comparative19.91 3.43 2.59 2.42 Example 4

TABLE 5 Eop 5% EL (%) LWR (nm) MEEF (nm) Example 2 15.13 5.32 2.13 1.82Example 3 14.82 5.69 2.26 1.79 Example 4 15.32 5.73 2.19 1.83 Example 513.78 5.78 2.21 1.73 Example 6 13.91 5.82 2.31 1.69 Comparative 20.323.21 2.62 2.32 Example 5

TABLE 6 Eop 5% EL (%) LWR (nm) MEEF (nm) Comparative 20.32 3.21 2.622.32 Example 6 Example 7 17.12 3.12 2.31 1.81 Example 8 16.72 5.98 2.351.76 Example 9 18.12 6.32 2.28 1.75 Example 10 17.91 6.42 2.23 1.74

As shown in the results above, the resist composition of the presentinvention exhibits excellent Eop, EL margin, LWR and MEEF.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A resist comprising: a base component (A) whichexhibits changed solubility in a developing solution under action ofacid, a solvent, and an acid generator component (B0) comprising acompound (B0-1) represented by general formula (b0) shown below:

wherein Rb¹ represents a perfluoroalkyl group of 1 to 4 carbon atoms, anitro group, a hydroxy group, a cyano group, an acyl group of 1 to 4carbon atoms or a halogen atom; Rb² and Rh³ each independentlyrepresents an unsubstituted phenyl group; and X1⁻ represents amonovalent counteranion capable of generating a strong acid.
 2. Theresist composition according to claim 1, which further comprises an aciddiffusion control agent (D).
 3. The resist composition according toclaim 2, wherein the acid diffusion control agent (D) comprises acompound (D0) represented by general formula (d0) shown below:

wherein Rb¹ represents an electron withdrawing group; Rb² and Rb³ eachindependently represents an aryl group which may have a substituent, analkyl group which may have a substituent or an alkenyl group which mayhave a substituent, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X2⁻ represents a monovalentcounteranion capable of generating a weak acid.
 4. A resist compositioncomprising: a base component (A) which exhibits changed solubility in adeveloping solution under action of acid, a solvent, and an aciddiffusion control agent (D) comprising a compound (D0) represented bygeneral formula (d0) shown below:

wherein Rb¹ represents a perfluoroalkyl group of 1 to 4 carbon atoms, anitro group, a hydroxy group, a cyano group, an acyl group of 1 to 4carbon atoms or a halogen atom; Rb² and Rb³ each independentlyrepresents an unsubstituted phenyl group; and X2⁻ represents amonovalent counteranion capable of generating a weak acid.
 5. The resistcomposition according to claim 4, which further comprises an acidgenerator component (B) which generates acid upon exposure.
 6. Theresist composition according to claim 5, wherein the acid generatorcomponent (B) comprises a compound (B0-1) represented by general formula(b0) shown below:

wherein Rb¹ represents an electron withdrawing group; Rb² and Rb³ eachindependently represents an aryl group which may have a substituent, analkyl group which may have a substituent or an alkenyl group which mayhave a substituent, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X1⁻ represents a monovalentcounteranion capable of generating a strong acid.
 7. A compound (B11)represented by general formula (B11) shown below:

wherein Rb¹ represents a perfluoroalkyl group of 1 to 4 carbon atoms, anitro group, a hydroxy group, a cyano group, an acyl group of 1 to 4carbon atoms or a halogen atom; Rb² and Rb³ each independentlyrepresents an unsubstituted phenyl group; and X11⁻ is a counteranionrepresented by any one of formulae (b11-1) to (b11-3); Rb¹⁰¹, Rb¹⁰⁴ andRb¹⁰⁵ each independently represents a cyclic group which may have asubstituent or a chain-like alkenyl group which may have a substituent;Rb¹⁰⁶ to Rb¹⁰⁸ each independently represents a cyclic group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent;provided that Rb¹⁰⁴ and Rb¹⁰⁵ may be mutually bonded to form a ring;Rb¹⁰⁶ and Rb¹⁰⁷ may be mutually bonded to form a ring; Rb¹⁰² representsa fluorine atom or a fluorinated alkyl group of 1 to 5 carbon atoms;Yb¹⁰¹ represents a single bond or a divalent linking group containing anoxygen atom; Vb¹⁰¹ to Vb¹⁰³ each independently represents a single bond,an alkylene group or a fluorinated alkylene group; Lb¹⁰¹ and Lb¹⁰² eachindependently represents a single bond or an oxygen atom; Lb¹⁰³ to Lb¹⁰⁵each independently represents a single bond, —CO— or —SO₂—.
 8. Apolymeric compound (A0-B11) comprising a structural unit derived from acompound (B11-01) represented by general formula (B11-01) shown below:

wherein Rb¹ represents a perfluoroalkyl group of 1 to 4 carbon atoms,nitro group, a hydroxy group, a cyano group, an acyl group of 1 to 4carbon atoms or a halogen atom; Rb² and Rb³ each independentlyrepresents an unsubstituted phenyl group; and X11-1⁻ is a counteranionrepresented by any one of formulae (b11-01-1) to (b11-01-3); Rb²⁰¹represents a chain-like alkenyl group which may have a substituent;Rb²⁰⁴ and Rb²⁰⁵ each independently represents a cyclic group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, provided that at least one of Rb²⁰⁴ and Rb²⁰⁵ represents achain-like alkenyl group which may have a substituent; Rb²⁰⁶ to Rb²⁰⁸each independently represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent (provided that atleast one of Rb²⁰⁶ to Rb²⁰⁸ represents a chain-like alkenyl group whichmay have a substituent); Rb¹⁰² represents a fluorine atom or afluorinated alkyl group of 1 to 5 carbon atoms; Yb¹⁰¹ represents asingle bond or a divalent linking group containing an oxygen atom; Vb¹⁰¹to Vb¹⁰³ each independently represents a single bond, an alkylene groupor a fluorinated alkylene group; Lb₁₀₁ and Lb₁₀₂ each independentlyrepresents a single bond or an oxygen atom; Lb¹⁰³ to Lb¹⁰⁵ eachindependently represents a single bond, —CO— or —SO₂—.
 9. A resistcomposition comprising: the polymeric compound (A0-B11) of claim 8, asolvent, and optionally a base component (A) which exhibits changedsolubility in a developing solution under action of acid.
 10. The resistcomposition according to claim 9, which further comprises an aciddiffusion control agent (D).
 11. The resist composition according toclaim 10, wherein the acid diffusion control agent (D) comprises acompound (D0) represented by general formula (d0):

wherein Rb¹ represents an electron withdrawing group; Rb² and Rb³ eachindependently represents an aryl group which may have a substituent, analkyl group which may have a substituent or an alkenyl group which mayhave a substituent, provided that Rb² and Rb³ may be mutually bonded toform a ring with the sulfur atom; and X2⁻ represents a monovalentcounteranion capable of generating a weak acid.
 12. A compound (D11)represented by general formula (D11) shown below:

wherein Rb¹ represents a perfluoroalkyl group of 1 to 4 carbon atoms,nitro group, a hydroxy group, a cyano group, an acyl group of 1 to 4carbon atoms or a halogen atom; Rb² and Rb³ each independentlyrepresents an unsubstituted phenyl group; and X21⁻ is a counteranionrepresented by any one of formulae (d11-1) to (d11-3); Rd¹⁰ represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent; Rd²⁰ represents a chain-like alkenyl group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or an aliphatic cyclic group which may have a substituent,provided that 10-camphorsulfonate is excluded from formula (d11-2); Rd³⁰and Rd⁴⁰ each independently represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent; provided that,the carbon atom adjacent to the S atom within the Rd²⁰ group in formula(d11-2) has no fluorine atom bonded thereto; Yd¹⁰ represents a singlebond or a divalent linking group.
 13. A polymeric compound (A0-D11)comprising a structural unit derived from a compound (D11-01)represented by general formula (D11-01) shown below:

wherein Rb¹ represents a perfluoroalkyl group of 1 to 4 carbon atoms, anitro group, a hydroxy group, a cyano group, an acyl group of 1 to 4carbon atoms or a halogen atom; Rb² and Rb³ each independentlyrepresents an unsubstituted phenyl group; and X21-1⁻ is a counteranionrepresented by any one of formulae (d11-01-1) to (d11-01-3); Rd¹⁰⁰represents a chain-like alkenyl group which may have a substituent;Rd²⁰⁰ represents a chain-like alkenyl group which may have asubstituent; at least one of Rd³⁰⁰ and Rd⁴⁰⁰ represents a chain-likealkenyl group which may have a substituent; provided that, the carbonatom adjacent to the S atom within the Rd²⁰⁰ group in formula (d11-01-2)has no fluorine atom bonded thereto; Yd¹⁰ represents a single bond or adivalent linking group.
 14. A resist composition comprising: thepolymeric compound (A0-D11) of claim 13, a solvent, and optionally abase component (A) which exhibits changed solubility in a developingsolution under action of acid.
 15. The resist composition according toclaim 14, further comprising an acid generator component (B) whichgenerates acid upon exposure.
 16. The resist composition according toclaim 15, wherein the acid generator component (B) comprises a compound(B1) represented by general formula (b1) shown below:

wherein Rb¹ represents an electron withdrawing group; Rb² and Rb³ eachindependently represents an aryl group, an alkyl group or an alkenylgroup, provided that Rb² and Rb³ may be mutually bonded to form a ringwith the sulfur atom; and X1⁻ represents a monovalent counteranioncapable of generating a strong acid.
 17. A method of forming a resistpattern, comprising: forming a resist film on a substrate using a resistcomposition of claim 9; exposing the resist film; and developing theresist film to form a resist pattern.
 18. A method of forming a resistpattern, comprising: forming a resist film on a substrate using a resistcomposition of claim 14; exposing the resist film; and developing theresist film to form a resist pattern.